Over the last year social networking giant Facebook released new application programming interfaces (APIs) that allow web developers to easily embed Facebook functions in third party sites. The new APIs  may prove to be more popular than anyone could have predicted. A range of commercial and non-profit web sites have added functions such as Facebook “Like” buttons to their web pages – for example, there’s one near the top of every page on this site.

Developers can also use the new Facebook Connect API to link into Facebook’s authentication mechanism so people can log into a third-party site using their Facebook username and password. Facebook says developers can use the APIs to provide a single-sign-on environment so users need login to only one site and be automatically logged into others they are registered with. Facebook uses the OAuth 2.0 protocol for authorization, so developers can feel confident taking this route would not lock them into proprietary software.

A Hypervisor reported eve found some sites that automatically create Facebook events that people can then forward onto their friends, opening up the world of viral marketing to a massive new audience.

More information on what Facebook calls “Facebook for websites“.