ZCoin is a privacy focused cryptocurrency built on Ethereum. The ZCoin protocol enables anonymous transactions with cryptography that utilizes Zero-Knowledge Proofs (ZKP). ZCoin increases privacy on their network by using a coin-mixer contract that wraps transactions in a serial number and destroying wrapped coins once they have been redeemed.
Zcoin was the first cryptocurrency to use a Merkle Tree Proof (MTP) as its proof of work algorithm. Merkle Tree Proofs are an innovative solution to achieving network consensus, and can increase transaction time while reducing the centralizing tendency of ASIC mining.

BurstCoin is a cryptocurrency with a Proof-of-Capacity (PoC) consensus algorithm. Unlike most other cryptocurrencies, Burst's architecture uses a Tangle (similar to IOTA) instead of relying on a blockchain. It also utilizes ring signatures and other features, in what is called the Dymaxion. The Dymaxion implements layers of tangle-based lightning networks on top of the Burst blockchain. Each of these payment channels is opened in the form of a standalone colored tangle. Burst is also developing atomic cross-chain transactions (ACCT), that will allow for full decentralized trading between two cryptocurrencies.

Bitcoin Interest is a fork of the Bitcoin protocol that pays coin holders interest. Bitcoin Interest (BCI) allows users to securely earn interest payments without ever moving coins from their wallets. Bitcoin Interest's developers believe that paying interest, weekly or monthly, on inactive crypto-funds can benefit the entire cryptocurrency market by reducing volatility.
Bitcoin Interest (BCI) is the first cryptocurrency protocol to use the ProgPoW consensus algorithm. ProgPoW is a Proof-of-Work algorithm designed to reduce the centralizing tendencies of ASIC mining by making it easier for standard GPU devices to participate in the mining process.