AirSwap dex is using their exchange protocol called Swap. (ERC-20 only)
Kyber is a wallet that utilizes a network of liquidity providers to pay and convert tokens. (On-chain, ERC-20 only)
Request Network is a wallet/app (they compare themselves to Paypal) using the 0x protocol to provide liquidity (Off-chain, ERC-20 only)
OmiseGo a white label wallet protocol that will use Plasma to trade p2p off-chain
Tenx is creating COMIT, another off-chain p2p solution that works without a native token. I'm guessing this is like Plasma? and aims to work across all blockchains without creating a new blockchain.
OmegaOne dex I don't know what protocol they will be using but orderbook style exchange using their own reserves as well as liquidity from 0x relayers, centralized exchanges, etc.