This remixed video is rather amusing, though the background music is really annoying:

These have been around for a while, but GenderAnalyzer.com has worked for me for the few samples I fed it. You give it a blog URL and it tries to guess if it was written by a man or woman.

Ben Affleck’s parody of Keith Olbermann is pretty funny if you’ve seen the show before:

The best way to summarize it would be an a-capella John Williams medley with Star Wars lyrics, with all the singing by the same person… it’s quite amazing.