I've read that some people use a different color scheme for live servers, so that they are continually aware they are doing sth. dangerous. A completely different scheme is IMHO a bit too much and some of the color schemes are rather difficult to read - especially if you use e.g. a red background.

It would look quite good and would be very useful, I guess, to have a say 20px or 32px colored strip on the left hand side for some hosts running over the full height of the window where you can just select an arbitrary color. That would allow you to easily recognize specific groups of servers...