You can view the demo here. On the left is a thumbnail of the tree, on the right is the tree displayed "full scale", that is, you can read the labels of every leaf. In the middle appears a subset of any internal node labels. Top right is a text box in which you can search for a taxon in the tree.
You can navigate by dragging the scroll bar on the left, dragging the big tree, or using the mouse wheel (and you can jump to a taxon by name). It has been "tested" in Safari and Firefox on a Mac, I doubt it works on Internet Explorer. Getting that to happen is a whole other project.
The viewer is written entirely in HTML and Javascript, the underlying tree images (and some of the HTML and Javascript) are generated using a C++program that reads and draws trees, and I use ImageMagick to generate actaual images.
