I'll post my favorite OST of all...if you would like my taste, I bet I can help with a great amout of great OST.
First of all, OST from HAjime no Ippo
yuuzora no kamihikouki
I like one piece ost
(since my upload speed sucks i just give you download page)
has a hell of a soundtrack.
NHK Ni Youkoso's isn't bad, either. Ef Memories' OST and the vocal collections for Aria the Natural (easy listening) and Macross F (pop, I'd say) are worth picking up.
Driver's high -- OST GTO
Madlax - Holy place, Limelda, Enfan, Madlax main theme and others
.Hack (ALI Project - the best!))
Beck - rock never dies
if it`s necessary, i`ll try to find download links
Only OST I listened to was for a movie called Hana-Bi... and it was pretty damn good. The movie and the OST. Would you guys know something that isn't anime? :3
Otherwise, I'm not one for these things. They can be pretty, but I only ever find myself interested in a few songs at the most.