Identicon

An Identicon is a visual representation of a hash value, usually of an IP address, that serves to identify a user of a computer system as a form of avatar while protecting the user's privacy. The original Identicon was a 9-block graphic, and the representation has been extended to other graphic forms by third parties.
Invention.
Don Park came up with the Identicon idea on January 18, 2007. In his words:
A similar method had previously been described by Adrian Perrig and Dawn Song in their 1999 publication on Hash visualization, which had already seen wide use such as in the random art of SSH keys.