"The free-to-the-public JavaScript Tree component enables you to build customized tree hierarchies made up of pure cross-browser Dynamic HTML (DHTML) using object-oriented JavaScript. By providing the tree hierarchy that's common in most graphical user interfaces (GUIs), this component can improve both the navigation and the real estate of your web pages." It looks pretty cool, although it requires that Java be enabled, which seems like a sure-fire way to make JavaScript even more annoying than it already is.