iTunes is still missing a few "make a buck" features that I think would be as well received by customers as Google adwords. One is a link from artists in your playlist to the iTunes Music Store. You'd only have the link if there were selections available, and it'd be pretty unobtrusive. It's also missing quite a bit in the way of, "If you're library looks like/contains Artist X, you'd probably enjoy a quick listen to Artist Y." Free lower-quality mp3s and other advert-style jive would further help online music supplant not just CDs, but radio (the traditional "try before you buy") as well.

Can you imagine how record/CD companies would act if there'd been no radio to this point and someone invented it today? Wonder how those royalities would play out? Good luck with that one...

Oh, and Apple, please fix the iTunes skipping bug when I alt-tab between apps in Windows.