Urbit too. Thanks!
Edit: I have them under "decentralized development platforms" barring a better suggestion
Take the blockchain out of Etheruem, and you still have a pretty cool deterministic state-transition machine. My understanding of Urbit is very limited, but I believe it has a similar concept of Ethereum without a consensus protocol.
Ethereum is a transaction log with a consensus mechanism. Anyone can append to it. It's a scroll: any group or society can use apps that check the scroll to come to conclusions about the state of their interactions.
Urbit is a transaction log that only the owner can append to. It's a journal: users can safely append to their journal with any app, and their apps can read the whole journal to display data from multiple apps in desirable ways.
Although Urbit (like Ethereum) is precisely defined without dependencies, Urbit is not a consensus computation platform. It's for processing your own data on your own (virtual or physical) machine.
Consensus computing is incredibly inefficient and should be used only where absolutely required. Where consensus is not absolutely required, computing should be localized under the user's control. People often forget to include this component in their designs of the decentralized future. But in fact, Ethereum needs something like Urbit and vice versa.
One way to think about the difference between Ethereum and Urbit: it's like the difference between a superconductor and a regular conductor. On the one hand, superconductors are qualitatively different and fundamentally more powerful. On the other hand, there are no superconductors in your iPhone.
https://tools.ietf.org/html/draft-hallambaker-mesh-developer...