I posted yesterday about Spotify, but there is several other free music services available, so i thought id let you know about another one called Grooveshark.

The key differences between Spotify and Grooveshark is that Grooveshark needs nothing installed... it all works straight out the browser and Grooveshark has no advertisements.
This means you can run it on any PC, so in some ways is more flexible than Spotify, but the quality of the music on there can be a problem sometimes.... it appears that some of the music is copied from radio stations etc. as you occasionally will hear a DJ introduce a track. It can also take a while before a track starts to play.
Grooveshark also has a feature called Autoplay, that will play tracks automatically based on what it thinks you may be interested in.

If I had to choose, I would pick Spotify because the music is always spot on, and plays with such little latency, it feels like the music is on your PC rather than streaming over the web.

But as its free... who am I to criticise?