In a connected world, the killer business model is a platform. They are the new-school toll bridge businesses that Warren Buffett had love affairs with over his investing career. Mr. Buffett's toll bridge type businesses are car dealerships, railroads, residential real estate brokerages, insurance holdings, among others.

However, discerning value investors can buy platforms that can be far more valuable than toll bridges.

Digital platforms can scale quickly, globally and with little capital investment. Inherent in platforms is operating leverage, a very important attribute allowing the platform to spin off cash and earnings as it scales.

What are examples of platforms? Think about Web 2.0 and connecting people, buyers/sellers, etc. Facebook comes to mind. As does Amazon and its marketplace. Amazon Web Services is a platform too, connecting myriad web developers and small, medium and large businesses to its centralized computing power. For more obscure platforms, one must dig into microcap land. Health Insurance Innovations is developing an online health exchange. World Energy Solutions is building an energy broker platform that connects buyers and suppliers in a brutally efficient market with price transparency. Priceline, Expedia, Travelzoo are all platforms. The interwebs created the possibility for information-aggregating platforms to disrupt the old way of hiring agents to book travel. Any fragmented market that can be molded into a platform for consolidation on the internet is likely to be a valuable business.

I'm a big believer in Overstock and its third-party marketplace. When combined with the potential to code software to create, issue and exchange cryptosecurities in a P2P format -- Wall Street 2.0 -- another extremely valuable platform could emerge.

If you have any other platform businesses that you follow, please contact me on my twitter handle @indievestments. I am always interested in finding a great growth story on a platform based business model.