Piccolo is a toolkit that supports the development of 2D structured graphics programs, in general, and Zoomable User Interfaces (ZUIs), in particular. A ZUI is a new kind of interface that presents a huge canvas of information on a traditional computer display by letting the user smoothly zoom in, to get more detailed information, and zoom out for an overview.

Kinda cool -- You lose all your basic UI widgets but get a lot of functionality for free. It's subclassed from a JComponent (JAVA) so adding it to an existing app doesn't suck.