Widget Update

Widget Update ... Automatically check for updates to your installed third-party widgets. It supports Apple's software directory, DashboardWidgets.com, MacUpdate and Version Tracker. It will present you with a tidy link list of all the updates found, enabling you to read release-notes and download the the updates quickly and painlessly.

Amongst the key features are automatic update checks once per day or week, Growl notifications, powerful configuration possibilities and an extensive documentation built right into the widget (but you can also read the documentation in your browser).

Press Shift+H at any time to bring up the help, or click the help button on the widget's back.