I recently switched from a black & white scheme to a colored scheme. As of now I'm enjoying a black-greyish background with some nifty colors.

IMO, colored code makes the process much more fun. I'm not sure if it makes me more productive though, but I wouldn't rule it out.

Small screenshot: http://photos-f.ak.fbcdn.net/photos-ak-snc1/v2102/219/106/34...