I happen to love the look of a carbon fiber weave. That's why the background on my computer is carbon fiber, and you can do the same. I've compiled a few links that feature carbon fiber desktop wallpapers...just click on the images to get to the page where you can download the wallpaper:
Ebin Texture 1
Ebin Texture 2
This is my favorite one, and what I use as my background:
Learn how to make both of the above yourself in Photoshop.
This is a free texture that you can download as a pattern file in Photoshop. It comes in a few different sizes, so you can play a bit with it:
This one actually has an Apple logo on it, for you Mac guys.
Cool use of lines and different colored carbon fiber:
You can see my desktop here: