Okay, so if you've ever been to YouTube to watch anything other than a viral video, you have probably at least heard of Tobuscus. If not, go educate yourself, heathen!
This is one of my, and my friends', favourite songs of his. Pay attention to the detail in the animation--always something moving, even if it's only barely. Also, notice how well the animation 'flow's for transitions. This is really great: