After recently installing Firefox 3 RC1 beta and a couple of extensions, one of which being Ad Block. I noticed that Hulu (premier online tv/movie service) does not like Ad Block. For obvious reasons it stops the loading of in-viewing ads, but whats really funny is Hulu knows this. It displays this notice every so often, hopefully they aren’t tracking. 
Ad Muncher blocks their ads without them detecting it
not to mention the video ads at every other website.
and in every browser, including flock and safari as well as the main browsers.