Oh wait, I also did the stalker ads idea, or sort of. I believe that someone will come up with a successful solution for location-based mobile coupons. What we have seen with our project is that this idea clicks with customers, but it is hard to develop a scalable model to acquire local advertisers. Local business owners seems extremely reluctant to embrace the internet medium for some reason (even with some free limited service, free pilot programs, etc.).

I end again with a shameless plug: http://www.moqpon.com