That's a good point, about the ad's..
One of our Mods Gary doesn't use google ad's on his site for that very reason you stated,, he isn't trying to make money but I do have a good search bar on his site, cuz his members were asking for it :p
One of my first forums I ran was a anti-yahoo site. I wont get into the details of it all, but we had a points system like vb has now. The members would trade the points back and forth for prizes and "rare" ID's, we also provided game leagues and tournaments for the members.
I didn't have a single ad on the site, but made over 3 grand in a few months
Sometimes I miss those days, but that site had and still has ( I sold it ) was to much drama going on for the amount of time I have to work on my websites..