Google Docs has added new contextual menus to the document manager. You can right-click on a file or anywhere in the application to bring up appropriate menus and choose action. For instance, if you right-click anywhere, the contextual menu contain existing toolbar elements. Similarly, if you right-click on any file, actions like saving in different formats, adding star, deleting file and other options appear.
Google Operating System thinks that the future version of Google Docs will probably include features like Webster Dictionary and Encyclopedia Britannica integration, exporting documents as MP3 using text-to-speech technology and searching the web for selected text.

wrote, on September 1st, 2007
It didn’t think you could add context menus with AJAX. This is awesome!