OK, if you want your iTunes to work like your iPhone or iPod touch then there is this application called Cover Art which does it. Does quite work right in that the lyrics don't scroll but are incredibly tiny, but the cover does shimmer which is cool!
"Simplehelp":http://www.simplehelp.net/2007/05/22/top-10-itunes-addons-and-plugins/ has a cool list like:
iTunesMyWalkman which lets you take a Blackberry that looks like just a Mac OS X disk and synchronize iTunes playlists to it
iTunes Album Playlist Creator makes every album a custom playlist so it is easy to sync it.
GimmeSomeTune lets you download lyrics and albums. I had trouble actually using it
iTunes-LAME lets you use the higher quality LAME MP3 importer when you are ripping CDs.
Nlyrics also trys to do downloading. It seems to work pretty well. Like Harmonizer which is a dashboard widget.
"Cover Version":http://www.imagomat.de/coverversion/ is a visualizer that shows album art and then tiny lyrics