I suppose I aught to expand a bit on mine.
In my world, most sentient beings have two "souls"... the mortal soul and the immortal soul. They are two aspects of the same soul, seperate but linked. The mortal soul is what most people "use" in their daily life. There are a few exceptions though... First, all magic-users have an exceptionaly strong immortal soul... it's what allows the person to tap the mana of the world. Magic doesn't actualy come from the soul (unless you are a ki user), but it's a gateway to the magic. This has only one effect in game terms... a magic user (even a minor one), after being raised, can sometimes get... flashbacks... of the time they were dead. These most often manifest as dreams while the magic user is resting, normaly only after the magic user has pushed himself to the brink for the day and the immortal soul has mostly taken over to recover. In the dream plane (part of my worlds cosmology), only the immortal soul exists, and thus sometimes can "remember" things.
The other exception is celestials/fiends/halfs/dragons/half dragons, and that works as follows:
Celstials and Fiends only possess immortal souls. Thus, if you somehow killed one and raised it (theoreticly) it would retain full memory of what was beyond.
Half-Celestials and Half-Fiends possess a much more prominent immortal soul. (So does one subrace of elf that actualy has a number of celestials in it's early lineage). All halfs have the "flashback syndrom" that magic users have, but for non-magic users it tends to manifest only on nights of great stress. True magic users can sometimes activly remember little snippets, but never very much.
Dragons have _no_ immortal soul. None. They can never, under any cicumstances, be returned from the dead... when a dragon dies, that's it, gone. (Demon-Dragons are pure immortal soul, but they aren't really dragons, despite the name). As a result, there are also no dracoliches in my campagin... IMC, a lich is a mortal body controlled and powered by an immortal soul... much like a celestial, but a celestials mortal body is created to be controled by an immortal soul, a mortals body is not, and doesn't quite work right (rots, etc). And yes, this means in my campagin (GASP, sorry BADD members) dragons have no true "magic". They have very limited innate powers (Polymorph self, fire breath, the ability to fly when their wings shouldn't be able to support them, darkvision, and they can see invisible), but the best arcane scholars still havn't figured out where that comes from. It's not even "true" magic... dectect magic, dispell magic, etc... don't effect it's abilities.
Half-Dragons have an immortal soul because of their (demi)human blood, but their mortal soul is more dominent. Magic generaly feels... awkward, to half dragons. The exception is druidic arcane magic. (Druids are arcane in my world, not divine, again it relates to the cosmology and magic theory of my world), which they take to quite readily for some reason. This has no effect in game terms (A determined half-dragon could still become a caster if he really set out to do so), it's just a roleplay thing. In terms of what happens when you raise a half dragon though... they remember NOTHING, EVER... even magic users. Their mortal soul is too dominant.
*edit*
Further random tidbit: To someone capable of percieving the immortal soul in my world, a person with a strong immortal soul (such as a caster) has an "aura" of another person... Generaly a very "angelic" (or demonic, depending) looking representation of themself superimposed over themselves, like a hologram almost. A person with the right spell can see anyones aura, even a non-magic user. The only time an immortal soul "scars" is if it has died and came back... so you can tell people who have been resurected sometimes just by looking at their auras.