GimmeSomeTune is an application that extends iTunes' functionality.
With GimmeSomeTune, you can download lyrics and album covers without the user having to do anything - so that he can do things the computer can't do for him. Last.fm and remote control support are available for you at your fingertips. Furthermore, it shows you iTunes' currently playing song in a beautiful floating window, which you can hide with the push of a button, and it can as easily be brought back to the foreground.
Mac OS X 10.5 only.