I know a lot of us are big movie soundtrack buffs and I'm also sure that many of us have already heard about this site but I thought I'd bring it up.
www.streamingsoundtracks.com is an amazing site that specializes in all types of movie soundtracks. They currently have over 3000 movie/game soundtracks in their library with over 50,000 individual tracks. The site streams in 32k and 64k MP3 or aacPlus strams for free and as a VIP member you get access to a 128k stream. They work on a request/queue system where registered users search/browse the library and add their tracks to the playlist.
Overall it is a very cool site with a fairly active community and has turned me on to soundtracks from movies I never would have listened to otherwise!