Cool topic!
I keep the same general rotation -
Guitar Vader discography
SST Band discography (Sega's house band for many years, their live album is spectacular)
Any soundtrack from any Parodius game, so more or less the Parodius discography.
Let's Go Away - The Video Game Daytona USA Anniversary Sound Box (four CDs of the greatest upbeat video game music of all time)
Metal Slug Complete Sound Box (hours and hours of triumphant music)
Perihelion Radio out of Cincinnati via RadioTuna.com - RadioTuna.com is a great online radio service.
Alternatively I often have Chrontendo (or Chronsega or Chronturbo) running in the background when working on cosplay -
http://www.youtube.com/user/Chrontendo - it's a long running video program about playing every Famicom / NES game (or Mark III / Master System or PC Engine / TurboGrafx-16) in chronological order. It also serves as a snapshot of the greater video game industry throughout the years that the games were released. Kind of a more academic look at the history of popular video games. I've seen them all dozens of times but for whatever reason, having it on keeps my working pace up and has really expanded my Famicom / PC Engine / Mark III release knowledge.