last May I started doing this with last.fm and it worked out nicely. I take my top 15 artists played on my profile (excluding classical) and I deselect them for my iPod. That way I only am listening to artists that are new or just not heard in a long. I do this to stop having a habit of listening and overlistening to the same music over and over again.
here are the 15 artists I am not going to listen to for the next month (July 2 to August 1)
Nine Inch Nails
The Twilight Singers
This way I can see some of my older albums and other music get listened to for awhile.