Rage is an essential aspect of the Changing Breeds (Nuwisha and Ananasi aside). Rage is granted by Luna (or Helios, in some cases), and is stoked by the sight of environmental destruction. Though it drives one to Frenzy, it is also a wellspring of great power. By tapping into his primal fury, a Shifter can perform feats beyond his normal capabilities, allowing him to effortlessly (or at least more easily) lay waste to his foes.
Rage is very cool, conceptually. In application, however, it doesn't reflect supernatural anger that well. While the rules as they stand are quick and simple (which is preferable to some people), some people might want a system with more detail, and/or that simulates anger better. Read what I have below, perhaps you'll find something that suits you.
So below are three "fixes" to the issues I (and some others) have with the Rage rules, as written. These rules changes aren't dependent on one another, though they're compatible and can easily be used together. So you can use one option without having to use the others, or two without including the third, or whatever. Mix and match to suit your needs. However, some game balance considerations: Building Rage is a disadvantage, while floating Rage clearly increases the power and utility of Rage. So as not to either cripple or overpower Shifters, Storytellers should consider using these options together; they work well together, as each option will balance the other nicely.

Option One: Virtues
As it stands, Rage makes any Shifter as likely to Fox Frenzy as to go Berserk. For example, if something pisses a character off, he rolls his Rage rating against a difficulty set by the phase of the moon. Four or more successes, he goes into Berserk Frenzy. And, if something scares said Shifter, he rolls his Rage rating against a difficulty set by the phase of the moon. Four or more successes, he goes into Fox Frenzy. Hence, a Get of Fenris is as likely to run howling from silver knife as he is to tear the head off a smart-talking leech. I would imagine a frenzied Bone Gnawer or Corax would be more likely to flee from combat than a Get of Fenris or Rokea; there should be some simple mechanic to account for this. Leave it to me to supply one...
Shifters with Rage have the Virtues Self-Control and Courage. Characters have a free dot on both Virtues, and three discretionary dots for players to spread between them, during character creation; each Virtue dot beyond that costs two freebie points. This may not seem like a lot, but inexperienced Shifters often have difficulty controlling their Rage. Each Virtue has a rating from 1 to 5. Improving a Virtue costs current rating x 2 in experience points. Using this system, Virtue rolls now replace Rage rolls; whenever a Rage roll is called for, use the following rules instead. A Shifter's player rolls the number of dice in the Virtue whenever a Rage roll is called for, with the difficulty usually based on the character's Rage. No Virtue difficulty may be higher than 9, nor may it fall below 3.
Because the use of Gnosis requires a clear mind, Gnosis points may not be spent, nor a Gnosis roll made (for Stepping Sideways, use of certain Gifts, etc.) on any turn that a Virtue roll is made to prevent Frenzy. If a Gift's description contradicts this rule, then the Gift's rules take precedence.
Self-Control and Berserk Frenzy: When a character encounters something that may provoke a Berserk Frenzy (being attacked, when publicly accused of being "of the Wyrm,", being taunted by a fomor, etc.), the player must roll the character's Self-Control; spending a Willpower point adds a success to this roll. The base difficulty of the roll is the character's [temporary Rage + 2] (maximum difficulty 9), and may be modified by circumstances. A Garou in the throes of combat is likelier to go into a killing spree than if she were cut off in traffic; the first check would be made against a higher difficulty, while the last situation would probably call for a reduction in difficulty. Also, phases of the moon affect Self-Control difficulties for most Shifters (Gurahl being the exception): the full increases Self-Control difficulties by 1, while the new moon reduces difficulties by 1.
A successful Self-Control roll means the character retains control of herself, though a failed roll indicates she enters Berserk Frenzy; a botch sends her into the Thrall of the Wyrm. If the shifter is in Crinos (half) form, an additional success on the Self-Control roll is needed to prevent Berserk Frenzy (i.e., the character needs two or more successes on the Self-Control roll to not frenzy).
Courage and Fox Frenzy: When threatened by silver weapons, when suddenly attacked by a Bane, or when otherwise terrified, a shifter may go into Fox Frenzy. The player must roll the character's Courage, difficulty equal to the character's current Rage + 2 (maximum difficulty 9); a Willpower point can be spent to add a success to this roll. As with Self-Control rolls to avoid Berserk Frenzy, this base difficulty for Courage rolls may be adjusted by circumstances, as not all things will cause the same degree of terror; however, phases of the moon don't affect Courage difficulties. Even one success is enough to avoid frenzy, while a failed roll sends the character into Fox Frenzy. A botch on a Courage roll sends the shifter into the Thrall of the Wyrm, as mind-numbing terror will inspire the same atrocities as overwhelming anger.
Rank: Shifters of all types gain discipline and temperance with Rank, and those with experience and great responsibilities aren't as likely as their lessors to lose control of themselves. This is simulated by adding dice to Virtue rolls equal to the character's [Rank -2], and apply the result to Virtue rolls. (Note: Results below zero indicate no die pool adjustment, but not a Virtue roll penalty.)

Lerry is a Storyteller using the Virtues option. He's creating a small pack of young Garou to help the players' characters in the upcoming story. Each character has three dots to spend between Courage and Self-Control.
First is the homid Wendigo Ahroun; Lenny decides to give her Self-Control 2, Courage 3; in typical warrior fashion, she's hot-tempered but brave. The lupus Child of Gaia Theurge gets Self-Control 4, Courage 1, reflecting a tame wolf with little in the way of killer instincts, but with good impulse control from growing up around humans. Finally, for the homid Uktena Galliard, Lenny spends two freebie for an extra Virtue dot and invests two in each Virtue, creating a nice, balanced character with Self-Control 3, Courage 3.

Option Two: Building Rage
According to standard Werewolf rules, a Shifter begins combat full of Rage, which depletes as the character spends it during the fight. So in effect, he becomes progressively less angry, and thus less likely to Frenzy, as the battle continues. This seems counterintuitive to me. I tend to take the "Hulk approach" to Rage; it starts out low, and builds as the Shifter fights.
All Shifters that normally have Rage have a permanent Rage rating; this hasn't changed. However, all characters normally wake up each day (or night) with one point of temporary Rage. Certain events (notably combat) will cause a Shifter to gain Rage, while Rage is lost when it is spent.
Unless specifically stated otherwise, all subsequent references to Rage refers to the character's temporary Rage, of course, not his permanent Rage rating.

Triggers Seeing the moon the first time that night New moon: Crescent moon: Half moon: Gibbous moon: Full moon: Upon first entering combat: Being struck in combat Causes no damage: Causes bashing damage: Causes lethal damage: Causes aggravated damage: By silver or Wyrm-toxins: Being provoked or enraged: Being humiliated: Suffering a botch: Stoking Difficulty 10 9 8 7 6 7 10 9 8 7 6 8 8 7

Gaining Rage: Whenever a character experiences any of the following (see table, below), his player may make a stoking roll to gain temporary Rage. The amount of temporary Rage equals the successes rolled, up to the character's permanent Rage rating (a botch on this roll instead causes the shifter to lose a point of Rage). When making a stoking roll, roll character's permanent Rage rating against the stated difficulty. Willpower may not be spent on this roll.

Michelle's Pumonca, Lana Timber Jumper, wakes from a fitful sleep in the late afternoon (with a Rage of 1 out of 5), gathers her camping gear and pipe bombs, and walks west through the woods, toward the construction site (soon to be new condominiums built on her Pumonca ancestral land, assuming Lana doesn't take care of that first).
On the way, Timber Jumper suddenly takes a bullet in the shoulder; she avoids frenzy, but the Storyteller allows her to make a stoking roll (difficulty 8, as she took lethal damage); she gains one success, giving her a temporary Rage of 2. Lana locates the sniper behind a ridge to her left, and the Bastet ducks behind a rock for cover and to assume cougar form. Sneaking up behind the gunman isn't an option, as she has no cover, so Timber Jumper exits the far side of the rock and charges the gunman, roaring; she spends a point of Rage for an extra burst of speed (taking her back down to Rage 1). The confused man panics and fires wildly at the cat, missing; Michelle makes a stoking roll for entering combat (difficulty 7), and attains 2 successes, giving her three points of Rage; Lana leaps upon the man and makes short work of him. The werecougar assumes Homid form after healing the gunshot wound, grabs the man's gun, and continues on to the construction site. On the way, Lana Timber Jumper sees the gibbous moon rise in the eastern sky; upon seeing Selene's glory, the Storyteller allows Michelle another stoking roll (difficulty 7), but fails to attain any successes; her Rage remains at 3 for now.
Timber Jumper slows her pace and walks quietly as she approached the razed construction site, barren of trees and topsoil, and moves behind a clump of bushes thick enough to conceal her. Tables, bulldozers and materials littered the muddy ground where ancient trees once stood; the naked frames of the buildings were skeletal silhouettes against the darkening sky. Lana sneers at the site of at least ten armed men milling around the site, in addition to an assortment of construction workers. They were prepared for her; no doubt, they had heard their late ally's distant gunshot. The Storyteller agrees the sight is enough to allow another stoking roll (difficulty 8), and with one success attained, Lana's Rage is 4. Tonight promises to be a rough night, and that was assuming all her foes were human...

Option Three: Floating Rage
Rage that isn't spent, and that remains in the character's Rage pool, is Floating Rage. Floating Rage isn't spent; instead, it's used as an auxiliary pool from which extra dice may be drawn and added to certain die pools.
A character's Floating Rage is equal to his temporary Rage at the beginning of that turn; Rage spent or gained that turn doesn't affect his Floating Rage dice until next turn. A character may use any, all, or none of his floating Rage in any given turn. Floating Rage may be spent to add extra dice to split die pools; only those activities eligible for Rage point expenditures are eligible for Floating Rage dice, such as combat and certain athletic feats. (So Floating Rage doesn't add to dice pools involving diving, computers, juggling, etc.) Floating Rage dice may be divided any way the player sees fit, so long as no die pool exceeds the normal die pool for a particular action (so if a character has a Brawl die pool of 6 before splitting, Floating Rage may not be spent to bring a Brawl die pool above 6). Floating Rage refreshes at the beginning of every turn.

Adren Vladimir Bane-Eater, Shadow Lord Ahroun, has a Rage of 6 at the beginning of combat. He spends a point of Rage to assume Crinos form on the first turn, so at the beginning of the next turn the Ahroun has a Floating Rage of 5. Vladimir splits his dice pool to attack, dodge and attack again. Normally, he rolls eight dice to attack with his klaive, but three dice are subtracted from his first die pool, four from his second, and five from his third. This gives him an attack die pool of five for his first attack, four dice to dodge, and three dice for his second attack. Vlad uses his Floating Rage that turn, adding one die to the first die pool, and two dice to the second and third dice pools; this gives him six dice for his first attack, six dice to dodge, and five dice for his second attack.
Vladimir connects solidly with his first attack, dodges his inexperienced foe's clumsy counterattack, and manages to inflict a superficial but nasty wound with his followup slice. As his opponent is still up, the werewolf spends a point of Rage to gain a third attack, burying his klaive to the hilt in the breast of his foe and ripping her nearly in half with an upward pull. (If Vladimir hadn't defeated his opponent, he would have had a Floating Rage of 4 to fight with next turn.)
Vladimir Bane-Eater walks away from the howling, tattered remains of the Child of Gaia Cliath, laying at her horrified pack's feet, confident no other Garou will challenge his honor at this moot...

Special Rage Rules Some Shifting Breeds have Rage rules that don't mesh well with the rules above. For these special cases, I suggest the following changes. Ananasi and Nuwisha: Werespiders and Coyote-Shifters don't have Rage. However, Storytellers may allow Ananasi characters to their current Blood Pool as floating Rage; as blood must be drunk, the building Rage option isn't appropriate for these characters. Nuwisha that gain Rage through Gifts may use employ as Garou do. And as neither Breed are prone to Frenzy, the Virtues Self-Control and Courage aren't necessary for them. Gurahl: The building Rage option is ideal for werebears, as it reflects their slow anger and (mostly) even temperaments. Stoking rolls may not be made upon seeing the moon, when botching, or when the werebear is mocked or otherwise humiliated; they aren't easily riled to anger. However, genuine threats to a Gurahl's land or people will allow a stoking roll (difficulty 7), and stoking rolls in combat are made as for other Shifters. Gurahl Virtue rolls difficulties aren't affected by the phases of the moon. When creating werebear characters, Storytellers may choose to give them four dots of Virtues (as opposed to three), to represent their tendency not to fly off the handle quite as easily as Garou and others. Bear-Shifters are already diverse in how they apply Rage, and so don't have access to floating Rage. (If for some reason a Storyteller wishes to simulate a Gana character, Gurahl Rage rules work well enough.)