I recently posted about Grooveshark which dubs itself as an “online music community”.  I think Grooveshark is great when you know what you’re looking for, but other sites like last.fm and Pandora are fantastic if you want to hear something new.  Based on the Music Genome Project, the idea behind Pandora is simple:  you type in the name of an artist that you like, and Pandora finds similar music.  For each song you hear you can choose to strongly approve of the song (in which case you’ll hear more material like it), disapprove of the song (you’ll be streamed a new song right away), or let the song play through, where Pandora assumes you liked it.

One issue with Pandora is that you can’t easily control it like you can a standalone program like iTunes, meaning you hvae to have a browser open at all times, and you don’t get hotkeys.  You also can’t stream your Pandora music to an Airport Express like you can with iTunes.  PandoraJam for the Mac solves these issues, and also gives you the ability to record what you’re hearing (tagged and added to iTunes automatically) and also scrobble to your last.fm account.

There’s a program similar to PandoraJam for Windows called Pandora Jar which was reviewed at Lifehacker.