Most of the users must now be aware of iGoogle. If not, simply write the url http://www.google.com/ig, and sign in to your google account and start using iGoogle.
You can create Google Gadgets by adding the Google Gadget Editor on your iGoogle. It will let you create your own xml file, and you can preview your changes on the same iGoogle page.
A short example of Google Gadget is as follow:
<?xml version="1.0" encoding="UTF-8" ?> <Module> <ModulePrefs title="hello world example" /> <Content type="html"> <![CDATA[ Hello, world! ]]> </Content> </Module>
instead of Hello, world! above, you can start using your HTML over here, like:
<?xml version="1.0" encoding="UTF-8" ?> <Module> <ModulePrefs title="hello world example" /> <Content type="html"> <![CDATA[ <html> <body>Hello World</body> </html> ]]> </Content> </Module>
Also add My Gadgets, through which you can have a rough idea that how the other Gadgets are made and view their source codes as well.
You can also make Widgets for other domains, with the help of your Google Gadget, and submit them on www.widgetbox.com etc.