Enjoying a song on iTunes but want to check out the video? Stereoclip is a clever piece of Adobe Air software that automatically hunts down the music you're playing in iTunes on YouTube, then plays the video in sync.
There's not much more to it than that: just start playing the song in iTunes, then launch Stereoclip and it will hunt down its best match (as well as offering other alternatives). When the song changes in iTunes, it changes in Stereoclip as well. If you want to add a visual component to a playlist, it's a pretty handy solution.
Stereoclip is a free download for Windows and Mac, requires Adobe Air.