BurnDNS is a proposal for an efficient decentralized DNS system based on burning bitcoins. It emphasizes ease of implementation and the ability work with SPV clients.
In BurnDNS, anyone can register a new DNS entry by burning (i.e. destroying) bitcoins. Each time you burn bitcoins, you include a mapping from domain name to address. It's possible for one domain name to map to multiple addresses; in this cases, the addresses should be tried in order of the amount of bitcoins burned.
BurnDNS is simple because it uses only the Bitcoin blockchain; there is no other network required for BurnDNS to function. BurnDNS software can be implemented on top of existing Bitcoin libraries.
It's practical because it can be used with simplified payment verification (SPV) clients. This means that a BurnDNS client only ever downloads block headers and relevant transactions. This uses over 10,000 times less bandwidth than downloading the whole blockchain.