I tinkered with Gimp for a bit, and after coming to the realization that trying to animate layers with transparency so that underlying content is visible would be impossible, I decided on a gravel texture to animate behing the spinning logo. I thought maybe I would draw a kind of harness attached to the Ubuntu logo, and connecting to something differently in the banner. I'll keep the intersecting lines stable, so that even if the 2 animations lose sync, the 2 lines will connect.
I like to play with the Gimp, image editing software for Linux, BSD, Mac,Solaris, and Windows. I don't have any experience with Photoshop, but I've heard people say that you can do pretty close to anything in the Gimp that you can in Photoshop, except that there are a lot more plugins for the latter. Here are some of the images that I've done over the years, in no particular order. Edit: I added a few that were done in Blender as well. I hope it doesn't slow the loading too much!