It's easy to see why music videos are so popular with Source Filmmaker, the movie making tool with all of Valve's models included. A few interesting camera angles, some slow mo, and all that's left to do is add music. But as is the way of the internet, some of these amateur efforts have impressive skill on display.
In particular, I'm always impressed with how people get the lip syncing right. After reading the descriptions, and trying to make my own stuff, it's clear that a lot of work goes into something like this:
Now have some more:
Some of the dancing animations out there are great, though due to community sharing, they can start to look samey after a while. Probably the best example of that is in the repeated dance animations of the above "Money" clip. Which is why the ipiSoft tech has me excited -- using Kinect, it's like mo-cap tech on the cheap.
Here's its demo, which plays out like a TF2 version of Spy vs Spy: