Our buddy Sebastian dropped a link to a fascinating interview with Mr. Anison himself, Hironobu Kageyama, over on otaku2.com. Perhaps the most interesting tidbit from the interview is:

PG: What song are you most proud of?
KH: That’s tough, but I guess it would have to be “CHA-LA HEAD-CHA-LA.” No matter where I go, people are happy when I sing that song.

Having seen the man perform the song live as a part of the JAM Project concert at Otakon 2008, I can personally say that his smile is like none other when the lyrics are shouted back at him.