Seeing as I've not got a Apple Macintosh computer yet I'll have to settle for this nifty utility called Konfabulator which brings you a Dashboard just like that of Mac OS X Tiger, but for Windows!
If you're looking for more widgets then browse on over to the Widget Gallery for some great addons. The widgets that are included are quite stunning - they're fast and work well and complement your desktop. Just press F8 to just show the Widgets just like in Tiger! Hmmm now maybe I can create Widget that will allow me to post to my Wordpress blog?
Should you wish to create your own Widgets then following the tutorial here. Don't forget to ensure that you ensure your items are cross platform (Mac/Win) by following these tips