Whoa, check this video out by Anders Hatte. Everything in this video was done in AE apparently even the music which was made using audio effects such as tone and modulation, key framed to create the drums and melody. No plugs-ins or 3rd party apps were used either. That's pretty dope, considering the beat isn't actually bad, and After Effects is not made for audio creation or sequencing.
210% After Effects by Anders Hatte
He even kindly put up his After Effects project file to be picked apart and figured out. On the visual side, the faux 3D cubes, cylinders, and spheres were nicely animated, and the fragment mirrors were a nice touch. There's a lively bounce to the animation that's complex and clearly more than just an expression script.