John's Background Switcher keeps your desktop fresh and interesting by letting you choose specific images to display as random wallpapers. It even draws from the largest pool of wallpaper sources you can find online. It's one of the easiest, coolest ways to keep your wallpapers random at all times.
This program starts you off with a few random Flickr accounts mixed in with your own photos. Most of the pictures it gives you automatically are G-rated animal and nature shots. If you want, you can pull more photos from just about any photo-sharing app you can think of. It supports the obvious ones like Picasa and Flickr all the way down to random sites like Last.fm. You can set them to change every ten seconds, all the way to every week. The program lets you work with different pictures on multiple monitors and even crop pictures in one of about a dozen different ways. It has to always run on your computer to work, but John's Background Switcher uses a fraction of the power the similar apps suck up.
No matter how often you want your background to change, John's Background Switcher offers one of the best ways to keep it random. It's easy to tinker with, which is exactly what you want in a background-switching program.