Stumble into music

I'm a big fan of StumbleUpon, a super great time waster that stumbles through the Web finding all kinds of interesting stuff - bizarre, funny, hip, informative - on your choice of topic - art, fitness, funny, music. So, lately I've been stumbling through the music topic and came upon these sites that I think some of you might appreciate:

8tracks.com: Create, share or listen to others' playlists. They're short (8 tracks) and cover a range of topics and have the potential to expose you to music you've never heard before. You can also search lists by genre.
entertonement.com: Sound clips, sound bites and collections of sounds related to various topics, including hangovers, Transformers and video games.
citysounds.fm: The site allows you to listen to latest music from city's around the world. Just click a city and listen.
thevirtualpiano.com: Play the piano with a few clicks of your mouse.
songza.com: This site allows you to listen to, share and add thousands of songs and paired videos to social networking sites, blogs or phones.

If you have other music-related sites to share, please comment.