Over on the right, you'll notice a last.fm widget that shows the most recent tracks played in my iTunes. I don't normally listen to iTunes at the computer (although I'm doing so at the moment I type this, and perhaps this will inspire me to do more often), so it will usually only update when I sync my iPod every 2-3 days. But if nothing else it may point out a few more artists for you to check out - many of the tracks have a little play button next to them which will allow you to listen to them at last.fm.
UPDATE: I ponied up the $3 for a subscription, so now we have Absolute Powerpop Radio via last.fm on the site, too. My preliminary experience is that it's mostly the bigger name artists I have in my iTunes, but there were some other lesser-knowns in there.
SECOND UPDATE: Now that the radio has kicked in a while, I've noticed it's playing a lot more of the independent artists I've featured on this site rather than mostly bigger names, making it more truly Absolute Powerpop Radio.