Here's another Human-inspired (i.e., brown) desktop background. I did it when I was frustrated a few days back during the initial furor about the "new" theme photos.
I like(d) the human, brown-based, color palatte, so I figured I'd give the Gimp a whirl & see if I could come up with something I liked.
The background is a 1600x1200 png of layered gradients of two of the browns off of the official human palette, with an Ubuntu logo slapped on the bottom right corner.
It's nothing all that special, but I offer it up as another option for folks to use.
It's also now available at http://www.gnome-look.org/