Anith Gopal

There are many tools in the market that allow you to customize your pages’ cascading style sheets (CSS), but there are actually a very few that do the opposite—scan for all the CSS rules in the document and remove those that are not used. Cleaning out the CSS will not only reduce the bandwidth impact, but will also improve the performance of the browser (minimizing the time spent by the CSS engine to parse the style sheets).

The rest is here:
CSS Crunch: new IE Extension for developers