Muxtape is probably the best thing to hit the internet since Napster. Here are a few that caught my ear:

• http://electro.muxtape.com/ – guess what kind of music you’re going to get
• http://fuckingrad.muxtape.com/ – via the muxtape blog with the description “ONLY EPICS NEED APPLY”
• http://tokyosoundscape.muxtape.com/ – sometimes it’s easy for North Americans to forget that Japan doesn’t only do JPop
• http://dee.muxtape.com/ – electronic-ish
• http://ks.muxtape.com/ – another via the muxtape blog – chiptunes

Update: Muxtape is dead. Long live Muxtape