A thread-bump, but a worthy thread-bump. Especially for those recommendations. .hack GU has some amazingly good (and under-appreciated) music. The original Crystal Chronicles has some amazing music too, and FFVIII ... man, I need to re-add that to my collection. That is one of Uematsu's strongest OSTs.
Lately I've been listening to this fantastic vocal image album for Evangelion that I fell in love with over a decade ago and still love. It's "Refrain ~these songs were inspireed by Evangelion~" by Yoko Takahashi. The slow songs are just really good j-pop ballads. Only like 4 of the songs on the album have any tie-in to Eva, but it's good nonetheless.
If you want to hear some good jazzy, piano-centric stuff, there's a composer named Takeshi Abo that you'll want to follow. He's worked on a bunch of visual novels that RPGFan's own Neal Chandran likes: namely, the Memories Off series, and the "infinity" series (Never7, Ever17, etc).
To echo some previous posts...
Mesh, I friggin' love you for listing Drunkard's Prayer. The song my wife and I danced to at our wedding was "I Want You To Be My Love," and we still listen to that album. Frequently. I got the new one, wasn't super-impressed, but I like Ohio too (who doesn't). And Iron and Wine is a win.
Tooks mentioned the Fable soundtrack. of the three Fable games, I find the most recent to be the best, and it has great "chill" music.