I absolutely love the score for Silent Hill. Akira Yamaoka is phenomenal at setting the eerie mood for those games, not to mention the standalone listening quality.

I agree with this entirely

the Tony Hawk series has had some epic soundtracks. it was on those games i first heard RHCP, Clutch, Mastodon, and Reverend Horton Heat

Halo 3 has someamazing ambient tunes. The rock stuff is blah though.

I like the Orchestrated parts of that soundtrack the best. Very nice combination of electronic drumloops and strings.

The mother series (AKA Earthbound zero, Earthbound, Mother 3) Has my favorite music out of any game i've played. If you've never heard of them i highly recommend checking them out.

Final Fantasy 9 Soundtrack:

Emiko Shiratori- Melodies of Life

Jet Set Radio / Jet Set Radio Future Soundtracks and the Metal Gear Solid soundtracks.

Gotta second JSRF soundtrack. I really wish there was more music like that around.

Grim Fandango soundtrack. It had some awesome swing and jazz songs on it.