This one is a command line application that optimizes CSS code. It reduces your filesize 20-60% depending on your coding style, by stripping unneeded characters such as whitespace, tabs, newlines, and semi-colons. CSS Optimizer only eliminates characters that are not vital to proper display of the CSS file.
Free CSS Toolbox is a freeware productivity software for web developers who work with CSS code. It includes a simple CSS editor, a CSS Formatter / Beautifier, a CSS Checker / Validator and a CSS Compressor. It is free - so go and check it out 
Here you will learn how to reduce your CSS code with nothing than just a few lines of PHP code. When you use this PHP code your CSS stylesheet won´t be changed or rewritten so you are still able to easily maintain and update it.
This CSS Compressor gives you some possibilities to reduce your CSS code. There are different compression options including “Colours”, “Measurements”, “Rules”, “Properties” and some “Output options”.
With this utility you can compress your CSS to increase loading speed and save on bandwidth as well. You are able to choose from three levels of compression, depending on how legible you want the compressed CSS to be versus degree of compression. The “Normal” mode should work well in most cases, creating a good balance between the two. And if you are a CSS expert you can switch to the “advanced mode” for greater customization.
CleanCSS is a powerful CSS optimizer and formatter. With CleanCSS you can make your CSS code cleaner and more concise. This one is based on csstidy 1.1
The Em Calculator is a small JavaScript tool which helps you making scalable and accessible CSS design. It converts size in pixels to relative em units, which are based on a text size.
Here you find an overview of the most essential css hacks. (Damn… browsers can be a pain in the ass
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Blueprint is a CSS framework, which aims to cut down on your CSS development time. It gives you a solid CSS foundation to build your project on top of, with an easy-to-use grid, sensible typography, and even a stylesheet for printing.
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Tom: really nice interview and a great person i´ve met in twitter. i just wonder when calvin is sleeping, seems he is a...
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Rizzi: Hello, loved these…definitely gonna use this
Gopal Raju: Thanks for including my icon set! Gopal ProductiveDreams.com
chad: Nice interview, Cal. Of particular interest to me was the schedule question, since I have been wondering how you manage...
Carlos Bracho: because, I want to have my own Cards with my own design, with the konowledege that I’ve learned at...
mayhemstudios: @Chad Engle - Thanks for backing me up and the kind words. :) @David Airey - I must have built up my tolerance...