The coolness of Konfabulator is not only to do with how the program's been developed but also the enormous quantity of high-quality widgets you can freely get that have been developed by many people. In addition to the usual stuff - weather maps, clocks, system tools, games, etc - there are some very neat things such as a beautiful little iPod Mini widget that syncs with iTunes to give you a little iPod on your desktop. Or a neat little language bar widget that gives you one-click access to foreign-language characters that you can quickly select and paste into your word processor.
There are also RSS readers, network signal indicators and much more - check out the widget gallery.
Konfabulator was originally designed for the Mac, with the first version for Windows released last November. I tried it when that version came out, and was mightily impressed with the elegance in design and functionality of the application and the widgets.
There are other widget apps for Windows out there, notably those than run under DesktopX from Stardock. I'm a long-time user of Stardock's products - especially WindowBlinds and ObjectDock - but for me, the new version 2.01 of Konfabulator wins hands down for widgets and for sheer elegance. And this version is the result of an enormous amount of evolutionary development work if the version history is any indicator.
Konfabulator originaly cost $25, which I felt was just a little too pricey. You can try it out free for two weeks. And if you do decide to buy it, the good news is that the developers have now dropped the price to $19.95. And that's cool!