The latest batch of Chatter Labs apps include two packages that target developers.  Both include extendable classes that let you build your own functionality on the platform quickly and easily using the work the app developers have already done. 

In this first video, Herman Kwong shows you how to implement "Like" functionality using his Chatter Shelf, Stars and Actions Framework.

In this second video, Kevin Schraith shows you how to implement Autoresponse functionality using his ChatterBot Autoresponse package.

Would love to hear what you come up with.  Please keep me posted!

Chatter Labs apps are part of the Force.com Labs family of apps.  These are unsupported apps produced by internal developers on their own time.  If you have questions about them, please post on the discussion board.