cheating is bad, better to find a way to make money and everyone is still happy..
I was actually thinking of launching an idea to do with adsense and ppc programs..
The trick is , you cant force peole to click your ads or offer any incentives etc but if everyone who joins understand what they are supposed to do

everything is kosher.
i.e. if i and 100 other friends each noticed an interesting banner on each of our hundred friends pages and clicked it , we would all make 100 clicks per day. if we were getting paid $1 per click we would each make $100 per day just by clicking 100 ads