http://www.floppymoose.com/index.html

Better Ad Blocking for Firefox, Mozilla, Camino, and Safari
also works with the Thunderbird email client!

Tired of distracting ad images cluttering up your web experience, or even your email? Here is a simple way to keep many of these ads from displaying in your browser. The technique below works for any Gecko-based browser (Mozilla, Firefox, Camino, Netscape7). It also works for Apple's browser: Safari. See the special instructions for Safari below. And it even works with the Thunderbird mail client! See Thunderbird directions below. Also, check out the new notes on dealing with Flash advertising, below. Finally, I've improved the ad blocking based on user feedback. Already using it? Grab the latest for even better results.

How to use userContent.css with: Firefox/Mozilla/Camino/Netscape
You need to place the userContent.css file in the chrome directory of your browser user profile. The different browsers store your profile in slightly different places. For macos X, the profile chrome directory locations are:

Firefox: home:Library:Application Support:Firefox:Profiles:profilename:randomstring.default:chrome:
Mozilla or Netscape: home:Library:Mozilla:Profiles:profilename:randomstring.slt:chrome:
Camino: home:Library:Application Support:Camino:chrome:

Restart your browser to pick up the styles. Go to your favorite sites and see that many ad images are gone, but other images are still there!

How to use userContent.css with Thunderbird New!