Long ago I made a few backgrounds to make my desktop look nicer. You may use this however you wish, but if you use them online I request that you link back to this page and copy the image to another location to save my bandwidth. Myspace users seem to enjoy directly linking to images; luckily HCoop's current colo provider doesn't charge obscene fees for bandwidth as our ancient one did.
A rather nice background that I use on my laptop nowadays.
One of the first backgrounds I made; I put this together in a few minutes on an old OS X machine at school to show someone how to use GIMP.
Just bits of the GPL strewn about a blue background.
I had a picture of a face lying about, and so I ran it through some filters and got this.
A very large (1920x1200) gray tile mosaic. It looks particularly nice on a 24" screen.