Bowtie is a free application that allows you to control iTunes with shortcuts, submits your songs to Last.fm, and sports a very simple, yet very powerful, xhtml + css + javascript based theming system.
Download Bowtie 1.0 Beta 2
Requires Mac OS X 10.5 or greater
Download the Theme Starter Pack
11 Beautiful Themes by Laurent Baumann
If you're looking for a full featured iTunes browser, sporting CoverFlow and smart search, check out Cover Stream!
©2008 Matt Patenaude & Laurent Baumann.