A Google Search Gadget is perhaps one of those that are on the top of demand for custom websites. But the list is getting bigger opening serious possibilities to increase once again productivity and why not FUN.
Adding a Google Gadget to your personalized Google page or iGoogle is just a matter of browsing Google Gadgets  and clicking on the button "Add it now".
But now gadgets are starting to be supported in other personal google pages like GMail. The process is not that straight forward though and I think the "Add it Now" button will pretty soon change to a select box to allow users to include the Gadget in GMail, their own web pages and more! (Desktop perhaps ;-) For now those officially available Gadgets you can use from your own websites are listed in .
Here is how you get your Google Gadgets in GMail or other places capable of parsing XML defined modules (Google Gadgets specified by XML resources) Please be advise that not all XML defined modules will work from GMail. It will depend on how generic the final markup is.
1. Locate your "New Gadget URL". It is an XML file which so far can be found somewhere as part of the gadget main page. For example a good place to look for gadgets is of course the official Google Gadgets directory. Locate the "View Source" link to get the URL of the XML file (Gadget URL). Just as a reminder, you can copy the link right clicking in your browser BTW.
2. To add your "Gadget URL" to Gmail be sure you have available a Gadget called "Add any gadget by URL". To get it follow path: Settings|Labs|"Add any gadget by URL"|Enable|Save Changes"
3. Follow path "Settings|Gadgets". Locate "Add any gadget by URL".