http://louhi.kempele.fi/~skyostil/ar..._harmonica.swf
The guy, Yuri Lane, also has a website, yurilane.com, where there's more samples.
My friend and I have agreed that from now, whenever we get really bored in class, we're going to practice beatboxing, to keep ourselves occupied. Because this is just too cool. In the past, we've tried circular breathing as well.