Often a day later, or even just an hour, you smile at the pain and no longer feel the wound. - Friedrich Rückert
CSS Compressor
This tool was inspired by a similar one at Dark Rift Studios. This is, though, written in javascript so it's all client side (no transmitting your CSS to someone elses' server), and it has a few more capabilities, plus configurable options. It basically takes out comments and whitespace from a CSS file, which can save more space than you might imagine.