So where are the Google gadgets
If you use Google personalised homepage, you can add Google gadgets to them. A Google gadget is just an XML file (or more usually the XML output of some dynamic page) that is displayed. There is a well developed API and you can do quite a lot of nifty stuff with them. But they don’t seem to be that popular (searching for Google gadgets, with Google gets very few relevant results).
There are quite a few in their gadget directory but very little mention of them outside Google…