Playing with http://www.spotify.com/ allows you to search and listen to tons of tracks via its friendly interface.
Imagine you have your iTunes Library but suddenly there are millions of tracks to choose from, thne you have Spotify.
OK after your trial period runs out of about 20hrs then its £6 or so per month but that wouldnt even buy you 1 CD at todays prices.
I searched for a lot of stuff and it nearly always came up with the goods, The Hurts, Vampire Weekend, Elvis, Beatles, Ultravox, Sisters of Mercy, whatever !!!
You can tag them as favourites and create groups of tracks to play whenevr you like.