UPDATE: It looks as if they've taken the beta signup down. I've removed the link to what was the beta signup page. Try DesktopX from Stardock - it does the same thing as Konfabulator and already runs on Windows. :-)
Konfabulator on Mac OS X was the coolest eye candy I had ever seen. It gives you the ability to place "widgets" on/under/over your desktop - these "widgets" don't just look pretty, though. They are functional - doing everything from pulling news content to checking the weather to displaying CPU status. There's literally hundreds of different "widgets" written by the community available for download for free.
The cool part!? Looks like there is a Windows version in the works.
I can't wait...