For those of you looking for a solution to download all your files off the web and shut down your computer automatically when they are finished, you are in luck as there’s Firefox Autoshutdown plug-in that works on all types of computers including Windows, Mac, and linux. (Of course, linux, you could probably script something instead or just leave it on as linux is a lot more secure than everything else out there.)
For detailed instructions on how to use this plug-in,