MikuMikuDanceCup is a competition where you use MikuMikuDance program to create a video with.
Some entries.
http://www.youtube.com/watch?v=COiCJ_mcc1s -
http://www.youtube.com/watch?v=hRp4mxNAFtM - war starts at 1:30
http://www.youtube.com/watch?v=epA33-VJAXY
http://www.youtube.com/watch?v=1cBdvSX9pXI
Enjoy.