I set my Active Desktop to "View As Webpage" so no icons are visible. All my icons are on the Task Bar, which I set to "Autohide." I set the background color to black (the most "efficient" background color, technically). This provides for a very clean area for a picture/pictures. I'm constantly changing them, but lately I've been using Java applet-affected images rather than static images. I use a variety of applets to affect any picture. I can make a picture look like it's underwater, or getting rained on, or slowly (or quickly) changing color hues (very cool with anime or pictures of paintings). I have many, many java applets that I've picked up here and there.

Currently I have the picture from "Stormbringer," the sixth book in the Elric of Melnibone saga (painting by the awesome Michael Whelan) on my desktop, with a java applet acting on it that very slowly changes the picture's hue. I don't have webspace so I can't post it here (webspace is required because there are multiple non-image files involved, in addition to the image file).

For those interested in a nice tool for generating Java applets that apply very cool visual effects to images, check out this internationally friendly site:

http://anfyteam.com/index.html

Look at the image on the page. Run your mouse over it. Click it. This is a (very garish) example of but one of the applets. It can be applied to any image ... the possibilities are endless, as there are dozens of parameters that you can play with to control how an applet affects an image, and many different applets, affecting whatever picture you want ... very cool stuff.