Crazy yet pretty impressive www UI: the Windows 2000 Server Documentation (I guess this'll only work in the latest version of Windows Internet Explorer). Select with the mouse a couple of works, and a dictionary definition is automagically (read: dynamically, from the server, onto an already loaded page) loaded into a floating window. Select a sentence and just as magically it doesn't break -- it just doesn't load any definition. Beautiful. Now, to extend this functionality to the non Microsoft population... how?