dhtmlxTree is a wise solution how to
represent hierachically organized data.
dhtmlxTree can load its content from XML and
supports dynamical loading of sub-nodest so
it can handle large amounts of data. This
JavaScript tree menu has
cross-browser/multiplatform compatibility,
powerful client-side API, drag-&-drop (within
one tree, between trees), checkboxes
(two/three states) and customizable icons
(with javascript or xml).