Amazon Album Art Widget for Mac OS X's Dashboard
When you run into a song or album that iTunes is unable to find art for, what do you do? If you're not sure and you're on a Mac, check out Widget Foundry's Amazon Album Art Widget. It will quickly perform an album art search on Amazon.com's servers, which tends to have some of the albums that are missing from iTunes, for whatever reason. It's still not as good as TuneSleeve on Windows, but it's dead simple and certainly works well.