Backlinking and Xanadu
In Ghosts of Xanadu, we discover yet another innovative idea from the past -- a way to "move forward through the rear view mirror" as stated recently by someone on the SIGIA Information Architecture list.

"Backlinking crudely approximates the two-way linking feature of an early hypertext system invented by Ted Nelson called Xanadu. Nelson coined the term Hypertext—the linking of information and a system for viewing it—in 1963"

I think backlinking is a very powerful concept from an Information Architecure (IA) standpoint. It provides rich links back to sites that link to the current page. These often would be pages highly related to the current page in some way. It's kind of like the Google "related pages" concept, but more timely as it would constantly age off old referrers and add new ones as they appear. It also would appear as part of the current page as auxilliary navigation.

Related:
- Wired magazine archives of articles on Ted Nelson and Xanadu -- Nelson is a strange character.

- The Xanadu Project home page
"PROJECT XANADU MISSION STATEMENT:
DEEP INTERCONNECTION, INTERCOMPARISON AND RE-USE
Since 1960, we have fought for a world of deep electronic documents-- with side-by-side intercomparison and frictionless re-use of copyrighted material. We have an exact and simple structure. The Xanadu model handles automatic version management and rights management through deep connection. Today's popular software simulates paper. The World Wide Web (another imitation of paper) trivializes our original hypertext model with one-way ever-breaking links and no management of version or contents. WE FIGHT ON."

- "One profound insight can be extracted from the long and sometimes painful Xanadu story: the most powerful results often come from constraining ambition and designing only microstandards on top of which a rich exploration of applications and concepts can be supported. That's what has driven the Web and its underlying infrastructure, the Internet." -- Vincent Cerf comments on The Curse of Xanadu (September 1995)