For example, DNSCurve-enabled nameservers are in the form key.name.tld, cjdns addresses have a key fingerprint embdedded in the users IPv6 address, etc.
I highly recommend reading the excellent draft document from Usenet at the URL I posted, particularly the example of the "Western Wisconsin Computer Company". It is much clearer than my comment and my examples of the simple concept explained therein are probably not ideal (maybe even wrong).
From only a cursory review, I see cjdns as a network where one does not need a third party to: issue a name, issue a key, check a key against a name or a name against a key. Each user creates their own private key, their own public key and finally their own address from their own public key. Unless I am mistaken, users get public keys and addresses from other users, not from a third party.
