Songrefernce Turns Your MP3 Playlist Into A Video Playlist
I love useful tools like this. Songreference is a free download for iTunes (Windows only for now) and Winamp that searches for the music video of whatever MP3 you are playing at the time and then plays it synced to the song. That syncing part isn't trivial, and it makes all the difference. The plugin also has links to Wikipedia information on each song.