not in any particular order, but these animes had godlike OST's:
"will of the heart" and "requiem for the lost ones" from Bleach
Some of One Piece (ouverture from "the new world" by Antonin Dvorak; it was played on the last 3 min of Luffy vs Crocodile fight, also Ave Maria from Hiluluk arc... amazing!)
Simoun has a great OST (currenlty watching)
Code geass had a very cool 1st ending of season 1
Black Lagoon op was not bad
Hellsing Ultimate OVA 4 had a godlike OST
this may come as a surprise, but I loved ost from Berserk.
Ghost in the Shell (both Seasons) had very good ops/eds + OSTs.
well, its nearly 4am, so nothing else comes to mind.
ill go through my anime dvd's tomorrow and post more.