Light-Weight Identity (LID)
LID is the original decentralized web identity protocol. When originally developed in 2003/2004, its goal was to enable anybody to securely assert their digital identity from anywhere on the web, without needing permission from anybody, or giving anybody a veto over how they would represent themselves on-line. And so simple that a skilled developer could implement it over the weekend.
LID has been tremendously influential, first in the development of OpenID and Yadis, and then indirectly in the subsequent identity efforts of Facebook, Google and the like.
However, it's original mission -- to be people-centric, without depending on some large entity (whether government or internet juggernaut) -- remains unfulfilled. But eventually, we'll all crack the code how to make the internet decentralized again and then the time of LID or a protocol very much like it will come.
In the meantime, LID has been implemented in InfoGrid and various other places. It's useful there even if world domination is still a bit out. Here's some more info ported over from lid.netmesh.org: