Well if you have mozilla, your default homepage is set to Mozilla search bar (google search engine) When you type something, its the same thing as using google but from Mozilla. Link:http://www.google.com/firefox?client=firefox-a&rls=org.mozilla:en-US:official Do mozilla get $$ for every ad someone clicks?
i am sure they do get $$ the revenue is in millions according to story on official blogs of developer check http://news.com.com/2100-1032_3-6048377.html?part=rss&tag=6048377&subj=news
yes they do. THey collect revenue from it, was some article recently about how they got $72million from adsense from doing that. Can read more here: http://www.calacanis.com/2006/03/06/firefox-mozilla-corporation-mozilla-foundation-made-72m-last/