Namecoin

"Namecoin gets its name from its parent project, BitCoin. In fact, much of the code that is used within the Namecoin project is taken from the original BitCoin source and hacked to achieve the ends that its originators are trying to reach. That’s because ultimately Namecoin works as a currency, that just happens to have its own P2P DNS system built into it.

In fact, purchasing a .bit domain is actually a namecoin transaction. The difference between this and traditional DNS is that once you own your domain, it can’t be taken away from you, because this would require that the entire P2P platform is compromised. That said, domains still expire as normal, and you will still need to renew ownership every year." (http://memeburn.com/2011/10/p2p-dns-taking-ownership-of-the-internet/)