BPM Counter Widget... Tap the beat of the song you are listening to with your keyboard or your mouse, and the widget will compute the BPM and put it into iTunes. Then it's up to you to create some fancy smart-playlists using BPM (fast tracks for your work out playlist and slow track for your romantic nights…). It is also a nice and useful tool for DJs.
Version 1.0.2: A few bugs corrected.
Mac OS X 10.4 or later