I'd make a main division: classical and popular music. Then, choose a small number of countries. That is, the most important ones. For popular music:
- Germany
- Sweden
- Spain
- Argentina
- Brazil
- France
- Italy
- Japan
- (ex) Yugoslavia
- What else?
Our main problem is the lack of information. Some of us (Scissorman, Dankrsta, Number9Dream, Ikvat, Petula, Vegangelica, me and others) are providing that info at the
World Music section. But there's a "deficit" of German, Italian, Japanese and Scandinavian (in non-English languages) music.