Ravencoin is a blockchain created by the owner of Overstock.com. It is a use case specific blockchain for the declaration of ownership of digital assets. Ravecoin is a fork of Bitcoin, and was originally funded by Medici Ventures, a blockchain investment fund owned by Overstock.com.
Ravencoin's name is inspired by the use of Ravens in sending messages, and its blockchain is designed to carry statements of truth about who owns what asset. The developers created a new consensus algorithm called x16r to solve the problems of centralized ASIC mining. The algorithm is unique in that it consists of 16 different hashing algorithms whose order are randomly changed.

Sharechain is developing a Proof-of-Work cryptocurrency platform. Their network is currently fueled by the Ethereum-based SSS token. Their marketing materials are unclear and do not offer any information about its advantages.

Unobtanium is a Proof-of-Work (PoW) cryptocurrency that uses the SHA-256 hashing algorithm. It was designed to serve as a commodity and store of wealth that would be less vulnerable to price fluctuations. The coin's supply is limited to counter inflation, and UNO coins were distributed in a manner that would discourage centralization. UNO can be merge-mined with Bitcoin.