Google Web Starter Kit Ensure you're following the Web Fundamentals guidelines out of the box. CSS HTML Javascript SASS Tools
Pleeease Postprocess CSS with ease. Performs all treatments that a pre-processor shouldn't have to do. CSS Tools
Hologram A Ruby gem that parses comments in your CSS and turns them into a beautiful style guide. CSS Tools
Project Parfait PSD CSS Extraction, Measurements and Image Optimization Service for the Web. CSS Tools
Haxe An open source programming language. It can be compiled to all popular programming platforms. C++ CSS Flash HTML iOS Java Javascript
AngularGap A library of mobile-optimized HTML, CSS for building highly interactive apps. Built with Sass. CSS HTML SASS
SMACSS Scalable and Modular Architecture for CSS. A flexible guide to developing sites small and large. CSS
Toolkit by Project Titon Extensible front-end HTML, CSS, and JavaScript user interface components for modern web. CSS HTML Javascript
Overthrow A tiny, no-frills, framework-independent, targeted overflow: auto polyfill for use in responsive design. CSS Javascript
Myth Busting: CSS Animations vs. JavaScript, Guest post by Jack Doyle of GreenSock. Article CSS Javascript
Myth A preprocessor to write CSS without having to worry about slow browser support, or even slow spec approval. CSS