SVG masks. This is a very interesting technology. It allows us to create a lot of cool effects, even in IE. I created an example for one of my answers on toster.ru. It looks nice and it has been picked on CodePen recently, so I think I should share it here too.
See the Pen SVG mask example by Ivan Bogachev (@sfi0zy) on CodePen.
Simple UI framework. RSCSS, REM-based sizes, fluid typography and other nice ideas. This website is powered by it.