Pandora is a great on-line radio service. It makes it easy to find new music you'll like based on the music you already know you like. They stream radio to your computer and you indicate if you like the song or not. The more you listen, the better they get at figuring out your tastes.

Up to now, this has all run in a browser, and it's kind of a pain to get the radio going. But that's all changed now - they are now offering an adobe air application that allows you to put pandora radio directly on your desktop. And because it's based on adobe air, it works on both windows and mac machines.