Anyway dancing has always been very popular in Japan especially in anime. Here are a few anime dances that are very popular in Japan and even in the states among anime fans.
Hare Hare Yukai from The Melancholy of Haruhi Suzumiya. This is mostly popular as a group dance as shown here 3 to 5 people are best at doing this one seeing as in how each person has a couple of varying moves. You can often find people doing this dance at anime conventions in the United States. This song can be found at the end of The Melancholy of Haruhi Suzumiya episodes.
There are your most popular dances in Japan and in the United States. Of course there are tons more dances and such, and even recently more that have been popularized by the Vocaloid franchise and Hatsune Miku. There are even people making up dances like these every day. So go out there and dance!