Definitely an appropriate use of the cow bell
The song "Around the Bend" by The Asteroids Galaxy Tour has gained popularity, not because Apple used it to promo it's new iPod Touch, but because of the obvious cow bell usage. Apple was attracted to the song, primarily because of the cow bell.
Oh, and by the way, it doesn't hurt that the lead singer has an incredible voice. The band also rocks and it's nice to see the usage of multiple instruments.