At London's Blockchain Expo, 16,000 people exhibited, networked or just gawped at stands promoting businesses that were too complicated or obscure to get their heads round. In this podcast Charles Miller tries to make sense of it all with the help of Osmin Callis from nChain, Richard Kastelein from Blockchain News and Sergio Rigert from Gingr - a Swiss startup that's putting prostitution on the blockchain.