Willworkers
Some object to Awakened Willworkers having linear (static) magic, and have issues with sorcery compromising Mage's theme and game balance. I, for one, see no problem with it. Sorcery rules are a Mage rules set, after all.
Create a character normally with Mage rules, and allow the player to invest Sphere dots in both Spheres and Numina. Background points can be spent on both Willworker Backgrounds (Arcane, Arete) and those for sorcerers except Mana (as the effects of this Background is covered under Arete). Have the paths selected relate to the mage's paradigm or history; they could either have been a stepping stone to Awakening (part of the character's background), or were learned during or after study with her Tradition.
A total of five dots isn't a lot to distribute between both forms of magic, so this shouldn't be a balance issue. Most players will likely invest in Spheres more heavily than Numina when creating Mage characters, anyway; a character split evenly down the middle between Awakened and linear magic might well suffer from not being adept enough in either form of magic to excel. Plus, time and effort (freebie/exp) spent learning Paths and rituals can't be spent on Spheres, and vice-versa. Access to linear magic makes mages even more flexible, without overpowering them; linear paths, while limited in effect, aren't limited by the character's Arete and won't net her Paradox. Thus, having access to a little static (linear) magic obviously won't make a Willworker too powerful.

Blood and Sorcery
For an in-depth discussion of how Numina, blood magic and enhanced awareness interrelate (and conflict), go here.

Shadow Craft
A socially and metaphysically complex issue for the Garou and other Shifters, worthy of a page to itself.

Liberties With Hell's Mandate
Kuei-jin have access to powerful and versatile Disciplines, and all of them can access rituals without need of special magical training, making them potentially very potent mystics. However, they can't seem to assimilate other forms of magic; there's no Kuei-jin equivalent of blood magic, and any magics they wield have to fit within the framework of their Disciplines and rituals. No vampire has ever been able to retain mortal magics through the ordeal of death, condemnation to Yomi, and the Second Breath. It's quite likely the duality of the damned Kuei-jin soul can't accommodate mortal sorcery any longer, though in turn this special state grants access to dark magics that no mortal sorcerer can wield.
While some Wan Kuei Disciplines bear resemblance to certain Mythic Paths, enough to suggest a possible relationship between them, this is probably due to different sorts beings accomplishing the same thing through different means. For example, feng shui has been practiced in the Middle Kingdom for millennia, and it serves to reason that both mortal magicians and undead would develop a set of mystical powers around it.
Dhampyr: On the other hand, perhaps the Hun-P'o split isn't an underlying reason for the inability of Wan Kuei to learn and use sorcery. After all, those rare dhampyr that have taken up the practice prove as capable in them as mortal magicians (though Spheres are still beyond them). Dhampir seem equally as likely to practice either Psychic or Mythic Numina.

Creation Hidden Bylaws
The origins of sorcery lie ultimately with the angels, who built numerous loopholes and hidden paths into their Creation, so they may manipulate and fine-tune it as they needed to. An analogy for this is a massive building (Creation) with numerous locked doors built into it. Those with the proper keys have access to the building (or some parts of it) so they may add rooms, make adjustments and repairs, and the like.
These doorways into the inner workings of Creation were meant only for the angels, though this was to change. After the fall, the fallen Elohim gave their mortal companions knowledge of some of these loopholes -- keys, if you will -- and thus the ability to manipulate and bypass reality in a controlled way. These keys were tuned to the unique souls of mankind, allowing them access to Creation that other creatures didn't have. After the fallen were locked away in the Abyss and mankind no longer had them to guide them, mortal sorcerers learned to forge their own keys, and perform new effects the fallen never conceived of (including magics that bound the once Stewards of Creation into service!). Other beings, from vampires to shapeshifters, exploited oversights in the structure of the universe as well, laying down structures and laws for their own unique powers. They all have the Angels of the Abyss to think for their power, though few have the courtesy to do so.
Ironically, however, the principles that guide sorcery aren't accessible to the fallen; they are demons clothed in flesh, not mortals, and can't use the special keys they granted their mortal charges so long ago. So while sorcery (and all linear magic) is possible through the subtle substructures of Creation laid down by the angels, the specialized loopholes in "reality" that magic exploits are inaccessible to them. Which matters not to most fallen; they built Creation, after all, and know the ins and outs of the universe's laws better than any. The versatility and power of a Celestial's Lores usually trumps mortal sorcery, making them unnecessary and redundant in many cases.
And this restriction doesn't apply to demon thralls, so many demons aren't completely without access to sorcerous powers, even if they're not the ones using them.
(It should be pointed out that Sphere magic is an actual circumvention, and often outright violation, of the "proper" magical laws that govern sorcery. The Spheres allow mortals to bend, dodge, warp and break the very laws laid down by the Elohim. This is an innovation no fallen had their hand in, and that few forgive.)