Here's a video of 26 genres (sort of a random number, no?) of heavy metal being crammed into one song.
Actually, it turns out that this YouTube user—DethPopVideos—was inspired by another 26-genre song that was posted by the guys from boyinaband.com.
"What I find amazing is that for one style of music I only had to come up with just a couple of sub genres to complete the alphabet," says the DethPopVideos guy.
Anyway, enjoy!