An extremely fast CSS parser, transformer, bundler, and minifier.
You may also be interested in ...
PaperCSS
The less formal CSS framework.
Koala
Koala is a GUI application for Less, Sass, Compass and CoffeeScript compilation, to help web developers to use them more efficiently. Koala can run in windows, linux and mac.
Driver.js
Kamran Ahmed has developed this light-weight, no-dependency, vanilla JavaScript engine to drive user's focus across the page.