This is a simple jquery plugin that mimics the Facebook textarea autogrow 
feature.

The difference with others in the wild is that it's fast, and by fast I mean, if 
you push <Enter>, the textarea will immediately grow (on keydown), not onkeyup.
It's a small difference but an important one in my opinion.  

Inspired (stolen?) by this: https://github.com/jaz303/jquery-grab-bag/blob/master/javascripts/jquery.autogrow-textarea.js