Namecoin is a blockchain-based DNS that allows users to register domain names with a ".bit" domain. Namecoin was the first fork of the Bitcoin protocol and it aims to remove centralized control over domain registration. It was the first cryptocurrency to use Auxiliary Proof of Work (AuxPoW) as a consensus mechanism,
where a child blockchain is dependent on the Proof-of-Work consensus of the parent blockchain. This allows for Namecoin and Bitcoin to be mined simultaneously, and when a new block is created on Bitcoin, it will also be added to the Namecoin blockchain.
Namecoin is a very important project that represents one of the best use cases of blockchain technology in protecting free speech and resisting censorship on the internet. It is powered by the NMC coin. The decentralized DNS provides more security from hackers and government intervention.

Stakenet is a blockchain with a unique Trustless Proof of Stake (TPoS) consensus mechanism that allows users to participate in the staking process without having to freeze their coins in the wallet. It's powered by the native coin XSN and is managed by its own masternodes. Stakenet (XSN) was created to build an ecosystem that allows easy and secure offline staking and cross chain communication. It has characteristics of Bitcoin, Dash and Peercoin, that were modified for their own purposes. XSN uses the Bitcoin Core, an improved Dash masternode architecture, and Peercoin's validation mechanism for creating new blocks.

Ignis is a blockchain platform that is being developed by Jeluirda; the company behind Ardor and Nxt. Ignis is a child chain of the Nxt blockchain. Jelurida is developing blockchain platforms that will enable users to develop decentralized applications, and will be based on a parent and child chain architecture.
Ignis allows users to create child chains with specific features and to create tokens that meet their needs. This project is closely related to Ardor and Nxt.