Do you use a SciFi theme or other type of theme on your desktop?
Have you changed icons or fonts on your desktop?
Have you remapped any of your system sounds?

I made it multiple choice

Most of my machines are pretty boring except for some wallpaper that I use (mostly NASA type stuff).

At work it is because I develop new applications on my box so I need to see it as a typical user would.... on a stock graphics Windows XP machine.

I customize the themes of my desktop

Blackbox For Windows looks interesting...

http://www.bb4win.org/

There is just no way I could run something like that on my work machines though. :(

That blackbox stuff looks really cool. I clipped it. I may try it out. If I do I will post about it.

I ran amok when I figured out I could customize icons. I'd just gotten GIMP with the cool logo generation filter and an icon creation app and just redid the whole place. Now my icons are beautiful, cool, and hard to figure out.