Nico Nico Douga have held the third "MMD DANCE MOTION CLIMAX-POLYGON MANIACS-" from 9:00 pm, December 23 to 11:00 pm, December 27 (JST). The event is for the dance videos using MMD (MikuMikuDance) software or other MMD compatible tools. MMD is a free tool for choreography of 3D character model (mainly vocaloids). This is not a competition event like MMD Cup, but you can still see the popularity based on the viewers count. Here's the announcement video for the event and the current top 3 videos as of this writing (11:00 am, December 25 in Japan).
No.1 (viewers: 24,969). "Poker Face"
No.2 (viewers: 10,627). "Just Be Friends"
No.3 (viewers: 8,490). "dance motion trace"