TrueUSD is a stablecoin backed by USD. It was created by TrustToken, a company that specializes in creating asset-backed tokens on the Ethereum blockchain. TrueUSD is fully collateralized and is transparently verified by third-party attestations.
TrueUSD was created within a legal framework that enables users to exchange USD directly with an escrow account. The platform is powered by smart contracts that ensure a 1:1 parity between USD and TrueUSD. Escrow accounts and regulatory compliance practices enable auditing and more legal protection for token holders.
Users wire funds to these third-party escrow accounts, and an equivalent amount of TUSD is generated to their ethereum addresses. Each TUSD can be redeemed for one US Dollar, that is held in escrow.

nUSD is a stablecoin that is pegged to the UD Dollar. It was created by Havven, a decentralized payment network. nUSD has a dual token mechanism that provides stability. In order to generate nUSD, users must acquire Havven Coin (HAV) and lock it in a smart contract. 80% of their HAV holdings remain in collateral, and 20% of its value is generated in the form of newly minted nUSD. This collateral staking mechanism includes an incentive mechanism that rewards users with a portion of the transaction fees that are collected when nUSD transactions occur on the network. nUSD is currently an Ethereum-based token, but will soon be transferred to EOS.

Dignity is a stablecoin pegged to gold, that was developed by the company Cryptobontix. Each DIG token is pegged to the worth of 0.02445 grams of gold, which was worth exactly $1.00 at the time of the Dignity whitepaper.
Cryptobontix's portfolio of stablecoins are based on a partnership with bullion suppliers. Each individual token acts as a security on a 15-year convertible mortgage. The DIG token is pegged to the value of gold. Every year, 1/15th of the tokens can be redeemed for gold valued at around $1.00.
Cryptobontix does not actually own all of the physical gold. The company plans on spending its profits on acquiring the actual bullion that token holders will have the option of converting.