As I will now reap of that fertile garden a handful of ripe new possibilities for PC backgrounds:
Man-child: a la Lion-O, a child developmentally, but a man physically due to an adolescence spend in cryogenic storage.
Wish-refugee: Often the wisher himself, the lone rememberer of a the reality that existed before the present one came to be. Somehow, the inhabitants of the new reality always seem to know that it is 'alternate' and temporary. Won't it be fun to prove them wrong?
Marooned time-traveller: This can also result in reality-warping ripples of causality, paradoxes, and maybe even mutual annihilation of different time-selves. I haven't watched Lost season 4 yet, so no spoilers, please.
Last Son of Planet X: I include this only because I suggested it in the title.
I Am The Egg-Fu of Earth-11: As above, but seriously, I hope someone plays this.
Sorcerer's Soul Trapped In A Slot Machine: This is from an episode of Thundarr. The slot machine will require a mode of locomotion--probably a levitating saucer of some kind. Self-mobility is a hard requirement for PCs, at least in my game. Unless. . .
Haunted Animal Skin: As in the Paul Kidd novelizations of White Plume Mountain and Descent Into The Depths of the Earth.
Victim of The Curse of Muppetflesh: As in the Angel episode 'Smile Time', and my post from yesterday.
De-powered Demon Imprisoned in Manflesh: Like Anya in Buffy. Could be orcflesh, ThunderCatflesh, of Skunkmanflesh, of course.