We've reviewed a lot of screensavers, but this might be the first one that we've encountered that kind of grossed us out. Fly on Desktop Screensaver does exactly what the name implies, adding crawling flies to your desktop in a surprisingly realistic way. It would make an excellent practical joke on an unsuspecting friend's computer, or just use it on your own computer to periodically creep out your co-workers throughout the day.
The screensaver appeared in our Display Properties menu along with the rest of our screensavers, and all we had to do was select how many flies we wanted. The default number is five, but you can have anywhere from one to 99 flies crawling across your screen. The flies materialize in the center of the screen and then crawl outward, gradually spreading with very lifelike fly movement. The effect of the screensaver is extremely realistic, and its grossness factor increases exponentially with the number of flies. When we dialed the number all the way up we did encounter some problems; the screensaver wouldn't stop when it was supposed to and we ended up having to quit it using the Windows Task Manager. But it handled more reasonable numbers just fine, and we were generally pleased with its performance. We think this is a unique and hilarious addition to your desktop; it's guaranteed to get laughs and probably some squirms, too.