I'll Have What Doug's Having
Doug Engelbart is The Man: he invented practically everything clever in recent computing, from the mouse through to hypertext. One of his lesser-known but more ambitious projects was the Open Hyperdocument System. Or rather is, since it's back as HyperScope 1.0:
The HyperScope is a high-performance thought processor that enables you to navigate, view, and link to documents in sophisticated ways. It's the brainchild of Doug Engelbart, the inventor of hypertext and the mouse, and is the first step towards his larger vision for an Open Hyperdocument System.
The HyperScope is written in JavaScript using the Dojo toolkit and works in Firefox (recommended) and Internet Explorer. It uses OPML as its base file format. It is open source and available under the GPL.
In practice, this sounds like fine-grained navigation and presentation of documents (although it seems to be much more). There's even a demo you can try out.
After just a brief perusal of this stuff, I can confidently say I don't really know what's going on. But if it's good enough for Doug, it's good enough for me. (Via Techmeme.)