Sandwich Lab sent along word of their app WebSaver
It's free for a limited time, too -- they've got a Twitter promotion
going on, so if you RT their message, you can pick up a free copy to try. There's also a trial version to check out as well that limits you to just four different sources, but in the full version you can cycle through to as many as you want, and even calibrate the view so you can get it just right. If you're looking for a screensaver that's a little more functional for your Mac, WebSaver may be it.