There are a few threads floating around with people who have used LED replacement lamps for color change or to brighten the cluster up. Some of them had spotting issues, though. Lots of good links to sources for LEDS or how to save cash and build your own. There's some info on aftermarket EL replacement lighting...someone used it but didn't like it and went back to stock.
This one should be particularly helpful:
zerothread?id=424429
Personally, I'm a big fan of the crisp white of the Q's gauges...one of my favorite aesthetic things about the car. But there are lots of options if you want to change things.