Since I normally roleplay while on the move - well, I'm usually on the move anyway - the kind of "music" that I listen to is usually the noise of the crowd, or if I have my earphones on, whatever random songs on shuffle in my mobile.

Even so, sometimes I would listen to soundtracks - JRPGs, movies, anime/animated films... Basically instrumental/acoustic/orchestral pieces. For example, [i]Final Fantasy[/i] OST when I'm working on [@Mr Allen J]'s Verthaven RP, and [i]Fate/stay night[/i] OST for the Sekirei one I'm doing with [@RyuHll].

(I'm more particular about having specific playlists for my personal novel projects than RPs.)