The GNU Name System
This might be an unpopular opinion, but I think that decentralized DNS, and decentralized naming in general, is one of the few use cases that can be neatly solved by a blockchain, but is extremely hard to solve any other way.A major problem when designing a decentralized naming system, or any naming system at all really, is preventing malicious users from grabbing all the cool names for themselves. The only way to do this is to make acquiring domains costly, and blockchains are a perfect way to enforce that in a decentralized manner. Other problems include accurately tracking domain ownership and letting the owners transfer domains to others, which cryptocurrencies have solved long ago. As an added benefit, because all domains in such a system are owned by a public key, we suddenly no longer need a root of trust for TLS, instead, we accept any TLS certificate signed by that public key.