The first one prompted the topic, what do you think:
Bedouin Soundclash - "Reggae - Pop", whereas Eddy Grant is in "Reggae"
Finley Quay, Deelite & Moloko are in "Pop" (there is a "Dance" category)
Only Black Sabbath, Frank Zappa, Jimmy Hendix and Slayer are in "Heavy Metal", but Biohazard, Pantera, Sepultura, White Zombie & System of a Down, SOD (amongst others) are in just "Metal" as are Sheep on Drugs, Sisters of Mercy and Nickleback.
"Rock" contains Gogol Bordello (he didn't think of adding "Gypsy-Punk") and Dread Zeppelin.
The Beastie Boys go in "Rock - Electric", as does Massive Attack, The Prodigy and The Streets
"Rock - Pop" contains Bjork, Nick Cave & The Cure (amongst others)