Hierachical WebListBox?


I want to display hierachical data (i.e. a tree with nodes and leafs) that the user also can modify (adding and deleting nodes/leafs, rearrange the hierachy, etc.). Drag and drop would be ideal, but just to show and update a hierachical list would be nice as a starting point.

As far as I could see, DesktopListBox could handle this, but what about Web 2.0? Or any other alternatives? Could anyone point me into the right direction here? Thanks!