Holo is a decentralized hosting provider that is built on top of Holochain. DApps can be set up and deployed with Holo hosting, as a decentralized alternative to Amazon Web Services, or other centralized hosting solutions.
Holochain is a protocol for creating decentralized Apps and is different from blockchain protocols in several ways. The main difference being that Holochain takes an agent-centric approach to their consensus mechanism, and has a different approach to validating value transfers.
The HOT token is used for paying for hosting services on Holo, and users can be paid for offering their computing resources.

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.

Ubiq is an Ethereum fork that aims to create a more stable smart contract platform for building DApps. Ubiq's protocol currently uses a Proof-of-Work (PoW) consensus mechanism, but will switch to Proof-of-Stake in 2019. The network is powered by the UBQ coin.
Ubiq's goal is to create a reliable and stable platform for developing DApps by modifying Ethereum's code base with important changes that will make it more secure and reduce instability. Consensus is based on their Flux Difficulty Algorithm, which is designed to constantly adjust the hash rate to protect against network attacks.