To locate extra widgets already on your computer, click the Dashboard icon on your Dock and watch the pre-installed widgets appear on a your desktop (clicking anywhere on the desktop will make them disappear again).
With your Dashboard open, locate the plus sign in the later left-hand corner. Clicking it will take you to a menu filled with more widgets that you can simply right-click to add to your Dashboard. If you change your mind, select the "Manage Widgets" button next to the widget set and a box pops up where you can uncheck widgets to make them go away.
If the you want more from your widgets than a ski report or stock ticker, be sure to check out the widget page of Apple's Web site for hundreds more to choose from. To install widgets from the site, click on "download" and it will magically appear as a zip file on your desktop. Double click the file, and follow the directions to install it on the Dashboard.
Leopard makes it super easy to create your own widgets but, thanks to the efforts of thousands of Mac users, there are tons of widgets available for free download on just about any topic and use you can think of. Well, maybe not yak shaving. At least not yet.