CodeIgniter - Open source PHP web application framework
Now this looks fab
node.js
Node's goal is to provide an easy way to build scalable network programs
Closure Tools - Google Code
Open source JavaScript compiler, debugger, library, and templating system from Google
Proudly Announcing: Modernizr | FarukAt.eş
Modernizr is a small JavaScript toolkit that uses feature detection techniques to determine whether or not the current browser is capable of any of the following features from CSS3 and HTML5.