Speaking about blocking,this firefox extension:
http://adblockplus.org/en/
block all kind of ad.I using it too,and everytime when i install banner rrom some sponsor i need to check how it look on site in IE since in firefox wont be visible.For example openx script which is most common choice for ad serving is totaly blocked,you cant even see images of that script if you installing it with firefox.
Site of adblock have alexa rank 32544 so i would say that is nice group of people not seeing ads.