Petname systems are naming systems that claim to possess all three naming properties of Zooko's triangle - global, secure, and memorable. Software that uses such a system can satisfy all three requirements. Such systems can be used to enhance security, such as preventing phishing attacks.
CapDesk — a desktop environment.
There is a Petname Tool extension available for Firefox that allows petnames to be assigned to secure websites. Use of this extension can help prevent phishing attacks. 
PetName Markup Language
The PetName Markup Language (PNML) is an XML proposal for using petname systems ubiquitously.
PNML consists of two tags: