RPGMemes

I was trying to figure out how many you could stack, just going by the SRD. I think the best you can do is:

Ghost Half-Dragon Half-Field Petitioner Worm that Walks Demilich Lich Pseudonatural Vampire Celestial Lycanthrope Fiendish Phrenic Paragon Human

That has everything but Skeleton, Zombie, and Half-Celestial. Skeleton and Zombie make you mindless (which keeps you from becoming a Worm that Walks) and require a skeleton (which a Worm that Walks doesn't have). Half-Celestial requires you be good or neutral, and turns you into an outsider, which only a Worm that Walks or Half-Dragon could undo. And it would work great with Half-Fiend if it wasn't for each one forcing an alignment the other restricts. I don't think any of the ones that don't change creature type change alignment.