Two OSTs that immediately pop to mind are Hellsing and Tsubasa Chronicle. Hellsing has some rather interesting pieces, instrumentals with a real attitude to them, and one piano piece in particular I should upload. Tsubasa just has a gorgeous score. Period.

Then if you have any love for jazz -- Cowboy Bebop. ♥ ♥ ♥ ♥ ♥ ♥

Hmmm . . . I'm sure I'll think of more, but I'll probably drown in my vast music collection in the process.