We have Dev, QA, and production SQL servers. I'd love to have windows dealing with each one to be assigned a separate background color, or the header and frame areas of the query analyzer.
So being able to color either by server or by database (or both), would be really handy. I'd call it an ergonomic feature that would allow us to standardize on interface cues to stave off dumb mistakes.
Voice of experience here. 😉