jTreeView

jTreeView is a jQuery plugin, written for jQuery 1.2.6, that allows you to easily turn a standard ordered list into hierarchical tree that is both check-able and collapse-able, and you can easily extend and control it as an object-oriented widget.
Why an another treeview based jQuery? The answer is: performance. As a treeview, it's possible that it contains many nodes. For example, we need to display all employees of an enterprise, the enterprise has 10+ department and each department has 100+ employees. Now, this plugin can support so large treeview because it do not create the whole treeview(create the treeview by html -- this is the job of server) and all event will be bound at the treeview instead of nodes of the treeview.
It, like jQuery, is licensed under either the GPL or MIT license.