Designed by Soldier Ant (his real name is Bryce Glass), the Flickr User Model attempts to map out the Flickr user experience. This is version 0.1, and I think he's working on version 0.3 now. Also linked on visualcomplexity.com
On his post on October 24, 2005, Bryce explains: "I've been doing some concept diagramming for work lately, and I've found myself enjoying it immensely. (...) However, since it's for work I can't share much of it. I did post some sanitized versions, with all the object-names obsfucated, but that just didn't seem wholly satisfying. So over the weekend I invested some time in a diagram that I can share with the internets: a simple Flickr user model (regrettably incomplete -- but I realized that if I tried to include the whole Flickr-verse that this diagram would go beyond labor of love and straight into excercise in folly)".Thanks Rex for sending in the link!