There is also the consideration that they could extend their offerings. People spend a long time on Facebook, especially when compared with the amount of time t

There is also the consideration that they could extend their offerings. People spend a long time on Facebook, especially when compared with the amount of time they spend on Google. If Facebook wanted to extend into search, or business applications, or anything online really, they are working with a base of close to a billion customers. That's a billion users who they have the opportunity to introduce a new service to. Any potential new service could provide a more effective platform for ads.