Wallpapr is a specialised search engine that tracks down images you can use as wallpaper on your computer.
As far as I can tell, all of the images returned are from Flickr, but there's no information on the site that says that's the case. If I'm correct, then I don't know what it is providing over and above a normal Flickr search.
I tried a couple of searches and some produced pretty good images, while the content generated by others was of questionable beauty.
Anyway, give it a go if you're looking for something new to personalise your workspace.
Unfortunately, I can't remember where I read about this service.