CSS Variables and the Pre-processors
Many have wanted CSS to get support for variables for years. It is great that support has landed on the WebKit side, even though many won’t be happy to mess up the clean solution with vendor prefixes :/
And then there are those who didn’t wait, and who jumped into pre-processor land. Sass and the Compas tool are the grand-daddies, and are doing well according to this recent poll. For awhile it seemed like Less would go way ahead with its closer-to-CSS-syntax, and easy ability to get going via less.js (no Ruby required). Sass fought back by bringing SCSS to bear, by having the awesome Compass tool, and getting great features such as blocks in 3.2.
I am personally a Stylus fan. I love how TJ took CSS and stripped the syntax and functionality to its core. Stylus feels to Python as Sass feels to Perl.
Whatever your poison, it is great to have these tools to make life easier and more fun.