Yesterday I read a story in the Times about a company that will give a totally free voice over IP service, the only thing that it does is that it monitors what you say during your call and it gives you ads of what you are talking about. When you are calling most of the times you're just staring at your screen and if on this screen ads popup I think this won't be disturbing. I think it's a great way to present ads and getting information while the user is talking about it.