Cozmo

Can someone tell me a good place to listen to sample clips on the internet? lets say I have a friend who downloads a lot of MP3's onto their computer (using WinMx which is like Kazaa, Napster). This friend oftentimes knows the name of a song or an artist, but may not be quite sure which song to download. Before spending the time/effort of downloading (and possible legal ramifications), is there a good web site to listen to 30 second or more clips? My friend has been using Amazon.com for this purpose, but they typically only have a few songs from every album with clips. Can someone give me some advice (for my friend)? If it matters, this friend likes alternative/rock music.