If you haven't tried out SVG wallpapers in Gnome, here's your chance to start!
The screenshot is shown with a blue to grey gradient background, but the actual SVG file has a transparent background. This means you can select whatever color or gradient you want, and the Ubuntu logo with multiple levels of transparency will sit on top of that.
Comments and variation ideas welcome.
If you haven't tried out Ubuntu Linux yet, you should do that too! :-)