How successful are online businesses with entirely ad-revenue based business model?
Google is a classic example of ad-revenue driven business model thanks to some very smart thinking behind Adwords and Adsense and some of the most innovative and market leading products like search engine, gmail, maps, youtube etc. I am wondering if there are other similar successful examples of ad-driven business models and if online startups offering free innovative products to niche target audience can survive entirely on revenue from ads…