I’m a sucker for soundtracks (technically, scores). I buy more soundtracks than any other type of music. Lately, I’ve picked up four that I’m enjoying very much.
Halo Reach has a good sound to. It’s not an album I’ll listen to very much but if I’m in the mood for some Halo it has a more modern sound than previous soundtracks.
On a related gaming note, I also purchased the soundtrack for Call of Duty: Modern Warfare 2. I’m especially fond of the opening titles music.
If you’re looking for good sci-fi soundtracks then I highly recommend Moon and Sunshine. I thought Moon was an excellent sci-fi movie. I’m still undecided on Sunshine (I need to watch it again) but it’s soundtrack is striking, especially a piece called Kanada’s Death, Part 2, which has been used in various commercials as well as the movie Kick Ass.
All of these purchases were made on iTunes.