I was incredibly amazed that a search for "desktop" "show off" and "wallpaper" did not yield any results to such a thread. Mods, please help me out here. Am I really the first one?
Anyway, I guess you know what to do here. I'll start out.
I used Valve's ASCII art of the Aperture Science logo as a terminal login message on my Linux system. But then I decided it might look cool as a wallpaper with a GIMP supernova in the middle. I tried it out and this is what I got:
I somehow find it very inspirational, with the light coming from the middle and the quote... If you want to see my Linux version, imagine a GNOME3 interface instead of a Windows taskbar...