Compass (which was built on top of Sass) does sprite sheet generation and cache busting. It's also shipped with a bunch of pre-defined CSS3 mixins. Sass also a

Compass (which was built on top of Sass) does sprite sheet generation and cache busting. It's also shipped with a bunch of pre-defined CSS3 mixins. Sass also allows you to put media queries inside your rule blocks. (In the future, this will be also possible in regular CSS.)