The avatar of new media, Ted Nelson, is always worthy of (re)consideration. YouTube brings his great project Xanadu to life (in a manner of speaking) with these brief demos.
Xanadu Spaces
ZigZag Data Structures
For the very tortured history of Xanadu, check out Gary Wolf’s article in the June 1995 issue of Wired magazine. And if you’re interested in what starts the Nelson story, checkout the great Computer Lib/Dream Machines.