Gadgets...

What are gadgets?
Gadgets are mini applications with a variety of possible uses. They can connect to web services to deliver business data, weather information, news updates, traffic maps, Internet radio streams, and even slide shows of online photo albums. Gadgets can also integrate with other programs to provide streamlined interaction. Gadgets are mini programs that give you information at a glance and provide access to frequently used tools. Windows Sidebar helps you to organize your gadgets.
Gadgets are small web applications that run on multiple sites, including iGoogle, orkut, other OpenSocial containers, Google Desktop, and thousands of sites all over the web that use Gadgets for Your Webpage. Gadgets are written in a module language using XML that wraps HTML and JavaScript.
What you can do with gadgets?
• Write in HTML; for dynamic behavior add JavaScript, Flash, or Silverlight.
• Get started quickly: no downloads necessary, no libraries to learn, and no webserver required.
• Create gadgets that run online in various sites — such as iGoogle, orkut, other OpenSocial containers, Maps, Desktop, and Calendar — as well as in third-party platforms and any webpage.
What you can do with Desktop gadgets ?
• Write in XML and JavaScript, optionally using C, C++, C#, or VB.net
• Use advanced functionality, such as:
o Free-form shapes and transparency
o Client libraries
o Responses to user actions outside the gadget (such as when the user opens iTunes or starts reading an email message)
Notes:
• Google Desktop must be installed on the user's computer.
• Not all gadgets can be added to a user’s desktop
Where do gadgets exist?
Gadgets are simply externally hosted XML files. They can be stored anywhere that normal web sites can be hosted. Google offers free hosting services that you can use to host your gadgets: Google Gadget Editor and Google Code Hosting.
Google fetches the XML specification when the gadget is displayed and caches it for approximately a few hours to prevent web hosting providers from being overloaded with requests.