Bootstrap by Twitter

I must say that the developers working at Twitter are VERY clever. So clever in fact that they invented Bootstrap which is a framework that allows for rapid prototyping of responsive mobile/tablet/desktop websites and web applications that are cross-browser compatible (IE7+), look extremely modern AND utilise some of the latest technologies such as HTML5 and CSS3.

As a front-end developer it is a MUST to be acquainted with Bootstrap and its genius, so do not delay, go here right away and get prototyping: http://twitter.github.com/bootstrap/index.html

In fact I built my portfolio website with Bootstrap in under a weekend: http://simplyspiritdesign.com/.