With Drupal you can easily construct Facebook applications!
Drupal has many modules for cooperation with Facebook. By connecting your Drupal site with Facebook, you can use Facebook to help spread your site. Common examples include using Facebook to login to an account, writing to a Facebook wall, and sharing Facebook events.
What is a Facebook application?
It is any application that works on Facebook. Due partially to the fact that there are no limitations on the functionality of Facebook applications, there have already been over 1,000,000 applications developed throughout the world. In addition to games, one can find applications that use Facebook's social graph, shopping applications, applications that utilize location information, and many more, and users continue to download new applications daily.
Digital Circus Facebook application development service
Facebook applications can be used in a variety of ways on both PCs and mobile devices. With content managed on Drupal as a base, one can present a Facebook application that handles a variety of devices including PCs and smartphones.
"Introduction to Facebook Application Programming" by Digital Circus CTO Tomoki Hasegawa