iGoogle, the gadget platform of Google now supports OAuth, and the interoperability of this standard was demonstrated by new iGoogle gadgets that AOL and MySpace both built to enable users to see their respective AOL mail or latest updates on MySpace, and keep track of your Google Book Search Library while on iGoogle. 

OAuth, which is a privacy-preserving security standard that defines how a user can give consent for their data on one website to be accessed by another website (or in this case a gadget). iGoogle never sees the user's password on the other site, and the gadget displays the user's data from the other site without storing any of it on Google's own servers (read more details about OAuth on our Security Blog). With these gadgets on iGoogle, users can now keep track of even more personalized information from across their online life.

If you want to create a gadget like AOL and MySpace, this overview will get you started on exposing an API that can be accessed using OAuth. If you already know which OAuth enabled API you want to access, you can jump directly to the gadgets documentation.

More info: Google Online Security Blog