LOL
If you sign up for like $5 a month, you can build unlimited custom stations, and save unlimited songs to their engine, and listen to them anytime you want.
Its pretty tight.
I've found a LOT of new music, by listening to artists stations, because they play similar artists when you type in a specific artist. IE... if you type in Radiohead, they will play predominantly Radiohead but they will also sprinkle in a little Oasis or Coldplay or whatever.
I have the slacker software installed on my mac at work, and its just a little icon that I can hide in the corner of my desktop or as a widget, but you can control everything fromnm your keyboard for those who need to slack undercover...
Let me know if you guys get down with it.