I like to listen to music while I work too. Just helps me focus by having something to tune out, I think. Depending on my mood it can be quiet stuff like pop or classical or something more lively like rock, techno or _meta_l. I've got a pretty wide range of music I like which can come in a number of formats (CD, ipod, online streaming).
Lately I've been hooked on Pandora an online stream radio tool that makes stations from an artist or song you put in. Kinda fun. You can rate the songs it pulls up that are similar to the one you entered so it can refine the station.
ATM I'm listening too my Maroon 5 station with Aviatic - "Goodbye Beautiful Day" playing. One of my all time favorite stations is my "Final Fantasy" station. It plays great modern classical music.
You can check out Pandora here:
http://www.pandora.com/