I had planned to post on this, and on reading sundancekid's thread on the sorry state of country music, it became imperative.
Check out
http://www.woxy.com. They style themselves the "Future of Rock n' Roll" and they play excellent modern rock!! I started listening to them at work and have discovered all sorts of great bands: The New Pornographers, Dios Malos, Her Space Holiday, The Minus 5, Immaculate Machine, and Sons and Daughters, just to name a few. They also play artists I've liked for a while, like Franz Ferdinand, Kaiser Chiefs, Tegan and Sara, The Bravery, The Killers, etc.
Give it a try. And also check out the Vintage Woxy feed for great "historical" modern rock, alternative and punk.