Underscore is a utility-belt library for JavaScript that provides a lot of the functional programming support that you would expect in Prototype.js (or Ruby), but without extending any of the built-in JavaScript objects. It's the tie to go along with jQuery's tux.
QuickUI (Quick User Interface) is a framework that simplifies the design, construction, and maintenance of web-based user interfaces. The easiest way to describe QuickUI is that it lets you write HTML as if you could create your own tags.
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.