With the release of Internet Explorer 4 and Windows 98, Microsoft introduced a curious little feature known as Active Desktop. The idea was simple: add web pages to your desktop that can be synchronized to work offline.
I'm calling my desktop items desk accessories, named after the feature of classic Mac OS by the same name. Little tools you can keep on your desktop.
There's little selection for now as a test run, but:
A tiny desktop pocket calculator
for basic arithmetic.
Width: 183 (185 for Gadget)
(I should point out that these were designed with IE 5's layouting in mind, and sizing will be wonky on modern browsers.)
Technically, yes! Using 8GadgetPack (if >7) and a 3rd party gadget called, suitably, ActiveDesktop, you can. I've rehosted it for your convenience. To add one, bring in the Gadget, go into its settings, and set the URL to what a screenshot above links to. Then set the width and height accordingly.