Free music sites

I like listening to music at work, but I don't have iTunes here, I don't have a connector thing that connects my iPod to my computer, and I don't usually have CDs on me. So I have to rely on different sites to get my daily dose of music. Here are the ones I like, and the pros & cons of each. Yes, this is what I do at work.

Imeem - This is probably the one I use the most. Imeem allows users to share all kinds of media- audio, video, blogs, photos. I use it because I can just search for playlists that people have already created, like "Coldplay Parachutes album" or "Amy Winehouse tracks."
Pros: Great song/video selection. You can create/save multiple playlists.
Cons: You have to register and create an account to use. Also, the loading time for songs has been pretty slow as of late.

Seeqpod - You can say it's the google for searching music and videos.
Pros: No login necessary, just search for music you want and play.
Cons: While the company touts that it reportedly has an index of 8 million songs, I've found that it doesn't have as big of a song selection as you would think. Searching can be frustrating at times.

Pandora - Internet radio/music recommendation service. You get a mix of artists familiar and new, based on your likes.
Pros: Discovering new artists who sound similar to artists you already like. Ability to vote on the songs you hear, which kind of influences Pandora's music recommendation service for other users.
Cons: Sometimes you're not in the mood to listen to new artists. And sometimes they can be very off in the 'if you like this artist, you'll enjoy this one..." feature. Also, Pandora's service is not available in non-US countries due to copyright issues.

Mixwit- Harks back to the mixtapes we all used to make before times of CDs and stuff. Cute cute cute.
Pros: You actually design a tape and you can get creative with the design/colors; it's a cool concept. Also, you can share your mixtapes with people.
Cons: The site gets its music from seeqpod, so see: seeqpod. You also have the option of searching from skreemr, which I do not like at all.