This screensaver's mesmerizing 3D graphics may hypnotize you, but its extensive feature set will snap you out of your daze. Sim Aquarium transforms your desktop into an aquatic arcadia. You can customize your tank with surface, bubble, and sound effects, and you can even import audio files to create a rocking aquarium.

The demo version includes five preset fish types and two tanks, whereas the paid version adds five tanks and lets you stock them with up to 41 species of fish. A word to the wise: Sim Aquarium takes up a hunk of hard-drive space and system resources, so make sure you have ample memory available. If you're looking for some aquatic magic for your desktop, this screensaver is for you.