A while back, John turned me on to something called the music genome project over at Pandora.com. You give it a band you like as a "seed band," and it'll go out and play a song by that band, and then it'll find a bunch of stuff from other bands that are similar in sound and play those songs. You have the ability to give each a thumbs-up or thumbs-down, and over time this will tweak your station more to your liking.
Unfortunately, I didn't have an internet connection capable of doing anything with that information at the time. Now that I have DSL, I've recently rediscovered the Pandora website, and I'm seriously thinking of buying this thing.
I got a tip on a fantastic group from Sarah over at OK Seriously, and used Jack's Mannequin as the seed band to create my radio station. So far I've discovered the following outstanding bands that are new to me:
Fielding, The GoStation, Josh Fix, The Stereo, Robbers On High Street, Ronan Keating, The Supernaturals, Wakefield, Evan And Jaron, The Skies Of America Move, The Whitlams, The Get Up Kids, Jonas Brothers, Voxtrot, The Apples, The Tickets and Golden Smog.
This thing is fantastic. Go try it for yourself. And if you like great pop music, go listen to Jack's Mannequin.