Like a Read It Later for CSS geeks. Curated. So you don't have to.

Mozilla Thimble

Mozilla Thimble makes it ridiculously simple to make stuff on the web. Thimble lets you make your own real, fully functional web pages in minutes. Then host and share them with a single click. Sharpen your web skills along the way. Easy, huh?

Great initiative.

In CSS

Pens picked by the Editors of CodePen

CodePen is now a public beta. Great tool.

In CSS

RefineSlide

This is nice.