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