black metal -- probably the most popular form of extreme metal of the 90s. It's extremely fast, grim and dark. It's executed with growling voice and open guitars. Typically, it features pagan, anti-christian or even stanic lyrics. (anonymous)

Classical New Age-- pretty self-explanatory, but has classical structure with a new age feel. (Mark Birmingham)

RIO -- aggressive, compositionally intricate rock, often instrumental, taking after 20th century experimental classical and jazz composers. Basically stuff that sounds like Henry Cow, who founded a collective of several like-minded bands called Rock In Opposition. The acronym for that organization has become the name for their sort of music -- that's why it's in capital letters, and has nothing to do with Brazil. (Michael Bloom)

skunk -- a mixture of ska and punk, sorta like Operation Ivy. (Emilia Ralston)

zeuhl -- aggressive anthemic jazz-rock, very powerful drums and bass. Basically stuff that sounds like the French group Magma, who also made up their own language, which is where the word came from, although I forget what it means. (Michael Bloom)