Here is the opportunity: how do you eliminate 50% of fraudulent clicks that you pay when you buy a campaign on Google? It seems like also Andre is talking about it too, here and here.
Well, to put things in perspective, 50% seems a lot, but it is not much compared to more than 50% which is lost on TV ads, and who knows how much which is lost on traditional banner ads sold on cpm (cost per thousand banner displayed).