I've recently started using the browser in itunes to get around my music library.

The problem being 'genre' is quite important (to itunes at least) and I've never taken much interest in it before. Until now! I'm addicted to getting everything assigned to a suitable genre, but so many geek-like questions arise.

Can artists cross genres?
Should Sigur Ros be listed as 'Ambient Rock' or 'Alt.Rock'?
Should Beck and Tom Waits have their own genre of 'Musical Genius'?
Are Green Day really a punk band?
What do I do when I've finished the first sweep? should I subdivide indie into separate categories...

Argh!