Bancor

The Bancor protocol is a standard that allows anyone to easily create completely liquid “smart tokens” that calculate their own prices & enable a single party to convert any token to another, without requiring a second party to exchange with. Thereby enabling the long-tail of completely liquid cryptocurrencies. Smart tokens hold other tokens in reserve, and can be used as decentralized token baskets (like ETFs), token changers (like shapeshift), project & protocol tokens (like GNT & REP), community currencies (like Ithacash & reward miles), and a lot of other use cases.