Here’s a fairly useless but fun freeware application for OS X: Backlight from Freshly Squeezed Software. What it does is display a screensaver of your choice as your desktop wallpaper. (Technically, it’s just a window laid over your wallpaper, but the net effect is the same.) Way better than using OS X’s built-in wallpaper slideshow.

It only works on the main monitor in a multi-monitor setup, and it can’t show RSS screensavers, but the price is right at exactly zero simoleons, and it’s a surefire conversation-starter when you fire up the ol’ PowerBook down at the local caffeination station/wireless hotspot. I find that a noise screensaver is not nearly as distracting as most others. Your mileage may vary.