Every once in a while, a website comes along that is so frivolous and absurd that it somehow morphs into pure genius. That's exactly what's going on over at MoreCowbell.dj, where you can miraculously add more cowbell (and a little Christopher Walken) to any song on your hard drive.
As this post is useless without an example, I hereby present you First Tube, modified to include 62% more cowbell — and about 37% more Walken, just for good measure.
Humor aside, MoreCowbell.dj actually uses some pretty sophisticated software under the hood. Specifically, they're tapping in to the The Echo Nest Analyze API, which generates an XML file describing a track's structure and musical content (including rhythm, pitch, and timbre) accurate to the sub-millisecond.
Glad to see all that technology going to good use!