Facebook launched a new applications feature  that will let you test the latest tools the social network is working on. Called Facebook Prototypes, it's similar to Google Labs as it allows you to try out new features that, as Facebook says, are "not quite ready for prime time, are a bit esoteric, or don't quite fit."

There are five new features currently available, most of which were created during a recent Facebook  all-night coding session where Facebook techies work on projects they don't have time to develop during regular business hours. Here's a breakdown of the five features you can try out:

Desktop Notifications (Mac OS X only): A Mac OS X growl notification app that sits on your menu bar and alerts you when someone writes on your Facebook Wall or sends you a message. You can also update your Facebook status within the application or navigate directly to your profile, News Feed, or Compose Message window.

Enhanced Event E-mails: Adds an iCal file to event notifications sent to your Facebook friends via regular e-mail. With one click, your friends can add the event to their personal calendar program like Google Calendar, Microsoft Outlook, or iCal. For this feature to work, your friends must have event e-mail notifications enabled in their Facebook account settings.

Facebook Prototypes are unfinished versions of products that are in testing that may have some kinks to work out. Some Prototypes may eventually launch to everyone on Facebook and become part of the Facebook experience, while others may eventually be removed from the Prototypes directory all together.