If you seen
Caramelldansen, you've seen an anime dance taken from Popotan. And there's
Tiny Little Snow Fairy Sugar, which we see a group dance move being done by some of the characters 55 seconds in.
End of Doujin Work, you see the various female characters from behind wearing their gym clothes and doing their own little dance. Although I must admit, Najimi has only one move and I think Tsuyuri got bored waiting. But the suggestion is that these are dance moves each of the characters came up with by themselves.
Later, as part of an AMV, I came across a Korean MMORPG called Yogurting, which looked like a high-tech music school setting where kids both dance and fight creatures. Never played it, but to me, there was a suggestion was you got points for doing various dance moves.
I'm thinking that most anime dances come from taking a popular move and tweaking it.
