The 24-million-user social networking site Facebook has announced that they are opening up their site to third party internet businesses and developers to build applications targeting the sites users and taking advantage of the social networking information that it holds. Facebook, a social networking site similar to and in direct competition with MySpace, has drastically grown in popularity over the past few years mostly with the younger high school and college crowds.

The official announcement launches with new web application features built on the open platform and offered by 65 online companies such as Amazon, Microsoft, Photobucket, Slide and various news organizations. The developers are able to make applications that show advertisements to users or they can build tools onto the site for transactions and interactions between users. The real kicker with this open platform is that all the revenue the third party companies generate, they are able to keep themselves. (At least for now.)

MySpace, which is the internet’s #1 social networking site right in front of Facebook, boasts a whopping 67 million active members, compared to the 24 million with Facebook. By opening up the platform to developers Facebook hopes to close the gap between themselves and MySpace by having more features and more useful tools offered to its user base. Mark Zuckerburg, the 23 CEO of Facebook, says he wants to consider the company a “social operating system” on the web.