GUI Icons purely made by CSS

These are GUI icons that are purely made on CSS with pseudo-elements and nothing more. Amazing what you can do with the latest CSS. These are experimental but they are awesome. These currently work on Firefox 3.5+, Safari 5+, Chrome 5+, Opera 10.6+.
Take a look at the icons in the below



You can find the demo for this here:

http://nicolasgallagher.com/pure-css-gui-icons/demo/

And you can find example exercise:
http://nicolasgallagher.com/pure-css-gui-icons/