Here you can download the free english version of the Miku Miku dance app.
What the hell is a miku miku dance? Well, if you’re a well rounded otaku freak (I’m not, but I play one on the internet) you’ll of course have heard of Vocaloid, and it’s mascot Hatsune Miku. Vocaloid is a program that allows you to make dialogue and song directly from text with computer generated voices, without having to go through the dangerous and tedious business of talking to a woman and or paying her to record some voice samples.
The app in question isn’t the vocaloid program (Which is commercial software) but rather a promotional doohickey you can use to animate a rather nice 3d model of Miku that comes pre-loaded and make your own music videos.
And no, you can’t take her clothes off. Though I guess you can make her flash her pantsu.