Mach Wallpaper is customizable so you can choose your own Quartz Composition, QuickTime movie or web page to put on your desktop, as well. In case you're not familiar with them, Quartz Compositions are a Mac OS X-only data type that allows developers to make 3D compositions. Many screen savers are Quartz Compositions.
About the web page support: you can add “desklets" (background images) automatically on a per-theme basis, and automatically customized and positioned for each theme. Or with the Desklet Manager, you can customize desklets' position, size, font, and colors (and add new ones) with a single click. You can put webpage desklets on your Desktop to view detailed info on weather (forecasted temperature, humidity, wind speed, etc.), dates, and more.
Another nice touch: if you have two displays, Mach Wallpaper will automatically detect it and take advantage of that. It supports Retina displays and allows each display to be independently customizable.
Mach Wallpaper is more resource intensive than simply having a photo or illustration on your desktop. However, if you have a recent Mac and an adequate amount of memory, you probably won't notice a performance hit. Also, Mach Desktop may cause problems with screen sharing, though it can be disable via a toolbar icon.
Also, if you have multiple programs open ALL the time, there's probably little use in a program like Mach Wallpaper. After all, it cool animations are running on your Mac, but no one can see 'em, what's the point?
Otherwise, Mach Wallpaper is a fun "eye candy" app and can truly bring your desktop to “life." It’s available at the Mac App Store for $2.99.
If you want more than still images on your desktop, Mach Wallpaper for Mac OS X (10.7 and higher) spruces up your screen with Quartz Compositions, QuickTime movies or even web pages.
It comes with 40 cool themes, each with 3D effects and/or True HD Video clips. 3D effects include Light, Water, Fog, Smoke, Clouds, Fire, Snow, Stars, Galaxies, Quasars, Black Holes, and more. The app also packs a video player foundation that can play full 1080P HD videos. Videos include Waterfalls, Fireplaces, Aquariums; and even historic landmarks like the Great Pyramids, the Roman Colosseum, the Athens Acropolis, the Eiffel Tower, and others.