I liked the math stack exchange design:
and think we can do something similar but different. I like how they keep the background clutter off of the questions and answers to improve readability. Thinking about something similar to graph paper (in terms of colors and easy on the eyes) but that is present in a lot of areas of physics, both experimental and theoretical, I came upon the idea of wave interference. So here's my contribution for a physics only design background (just a quick mock-up, not intended to be final in any way):
By the way, I joined the math stack exchange a few minutes ago and now I'm experiencing envy. They get a lot more traffic. Things get voted up much more quickly. I wonder if that will last; surely people are more interested in the physical world than in a bunch of dusty dry theorems.