Dock Tab Image
Using The Desktop Effects Tab

The Desktop Effects tab allows you to run screen savers on you desktop.  You may choose to have a desktop effect started at login.  You may also choose to have the effects rotated among your collection of favorite effects at a designated time interval.   If you select a higher value in the CPU usage popup, the screen effects will appear smoother but your system may slow down.  

Obtaining More Desktop Effects

Any screensaver may be used as Desktop Effect. Go to versiontracker.com or macupdate.com and do a search for "screensaver" or "screen saver" among the Mac OS X offerings. To install new screen savers, drag them into /Library/Screen Savers/ or /Users/YourUserName/Library/Screen Savers. The new screen saver modules will automatically appear in Visage the next time you open System Preferences.