NavCoin is a community-driven digital currency built on an open-source,Proof-of-Stake (PoS) blockchain. The project has an active development community, and places a strong emphasis on their user governance. NavCoin is developing a feature for its PoS consensus mechanism that will allow for cold staking. Users will be able to stake their coins while keeping them offline.

Primecoin is a cryptocurrency based on finding prime numbers. Identifying prime numbers plays a central role in cryptography. Primecoin's unique Proof-of-Work (PoW) consensus mechanism is able to increase transaction speeds and improve energy efficiency.
The network searches for special prime number chains known as Cunningham chains and bi-twin chains, which are of interest in mathematical research.