Here is more evidence to show that if your fans go to great lengths to do something, it should be a feature in your next game.
Apparently people have figured out how to create custom songs for the PS2 version of Guitar Hero 2.
My favorite one so far is the Dueling Banjos:
I like how it lulls you into almost boredom with the repetitive and easy-to-play chords, then, with no warning, all hell breaks loose. So great. It makes me laugh to see a song this complicated turned into a guitar hero song, and done right.