I've had too many to count ;p
one cool one was when i was on 5 hits of acid (they were supposed to be double hit but didn't feel like it), the sky turned hawaiian themed or something similar and fell apart in puzzle pieces, same day i talked to a ashtray full of butt's with distinct personalitys.
and on a handful of shrooms i was sitting in downtown seattle (the trees looked like they were out of lord of the rings or something) and the ground underneath me started glowing green with geo-pattrens and fell apart into some kind of abyss. thats only a few ones i can remember well enough to type out.
sleep deprivation hallucinations are lame, by the way. all i see are giant metallic orbs floating around, i usually get enough sleep though.