Maximum PC has an informative article about customizing the Linux desktop. It’s a great resource for people who have seen people talking about things like Compiz and Emerald and wondered what they were talking about.
One topic the article covered was desktop widgets. For GNOME, it recommends Screenlets, which is available in the standard Ubuntu repositories. This means you can download it by simply opening a terminal and typing in sudo apt-get install screenlets.
Screenlets comes with a variety of preloaded widgets, and the handy Get More Screenlets button. Since I don’t have a widescreen monitor and want to have some room for my Pidgin buddy list on the side, my widget desires are pretty simple. I went with the obligatory weather widget, a simple calendar, and a Vista-like CPU meter I downloaded from GNOME-Look. Here’s a screenshot: