Jewelcase is another incredible utility for the Mac. Jewelcase is a plugin for iTunes that displays the CD cover art and artist/track title/album title info in a very cool 3D spinning display.
My only grumble with it is that it doesn’t automatically retrieve the cover art; if it is not already in your iTunes library, it simply displays a generic CD cover. In the mean time, you can always use something like the FetchArt script to nab cover art for you.