cssmin.js is a JavaScript port of YUICompressor's CSS minifier.
The motivation
Minifying CSS helps reduce file sizes and makes your pages faster and your users happier. YUICompressor is cool but is written in Java, which can be a blocker for some folks - you know JVM, command line, classpaths... No more excuses, now you have a simple light JavaScript version. And as you know, JavaScript is everywhere, so you can run it however you want, integrate with your editor and so on.
The links
The integration
If you want to integrate the library into your environment, it's really easy. It's just one file with one function in it. So, just a simple function call:
var result = YAHOO.compressor.cssmin(input_css_code);
The credits
Julien Lecomte - creator of YUICompressor
Isaac Schlueter - he maintains the YUICompressor and is the author of the original cssmin utility which was ported to Java by Julien.
Ha, what about a quiz? Guess the language of Isaac's original cssmin and I'll send you a free copy of Even Faster WebSites and I'll sign my chapter. Seriously.
UPDATE: For Ruby folks, there's a Ruby port from the Ryan Grove.
