I'd be interested in compiling a list of sites that suffer from issues / breakage under Firefox and other browsers.
Here's a couple to start with :
Cork City - eeek!
Driving Test - forms don't work properly on firefox
AIB business banking - requires MS JVM
Although the Google terms of service do not allow you to discuss specifics, such as clickthrough rates etc., you are allowed to discuss your overall earnings.
So, if you are using Google Adsense, how much are you earning per month?