I recently heard of Konfabulator www.konfabulator.com when reading that Yahoo had bought them and they're going to be renamed Yahoo! Widgets

Konfabulator implements a pretty slick concept of "widgets" that are what you want them to be.

Combining the use of XML and JavaScript for implementing widgets definitely speeds up development.

Messing around with a widget I downloaded last night proved to be highly addictive.

They have a lot of widgets in the widget gallery.

I intend to release the updated Radar widget that I worked on last night.

Check 'em out, you'll like 'em.