Nash Exchange, formerly knows as NEX, is a decentralized exchange. Nash's decentralized exchange is powered by an off-chain matching engine that allows users to trade a variety of digital assets across several blockchains. The exchange's NEX token, gives holders the opportunity to stake tokens to earn a portion of the fees generated.

OmiseGO is an Ethereum-based financial network that enables greater inclusion and interoperability between blockchain projects. OmiseGo is building a decentralized cryptocurrency exchange that will facilitate real-time, peer-to-peer value exchange of fiat and crypto assets. Through the OMG wallet SDK, users can build or use compatible wallets to integrate with the network.
OMG is powered by their Plasma architecture and the OMG token. Their goal is to enable unlimited scalability to support greater transaction speed and higher trading volumes.

0x is a decentralized exchange built on the Ethereum blockchain that allows for ERC20 tokens to be traded. 0x hopes to serve as a building block for creating decentralized exchanges.
It is an open-source system of smart contracts that acts as a platform for those wanting to build with the 0x protocol. Augur, Aragon and several other projects are using 0x, at the moment.
The 0x protocol addresses some of the common issues that plague other decentralized exchanges. 0x is faster, more liquid, and less expensive to run. Its speed is due to reduced blockchain congestion. This is achieved by moving all transactions off of the blockchain and then verifying them. This move, also allows for the elimination of transaction fees by reducing the reliance on the blockchain. 0x doesn’t charge fees of any type to use the protocol. However, Relayers that create their own decentralized exchange can charge fees.
The 0x Project uses the 0x Ethereum token, known as ZRX, that allows users to pay Relayers’ transaction fees. It is also a decentralized form of governance for the 0x protocol system. Anyone holding ZRX can give input about improving the protocol.