I can't imagine wanting this. When I press ALT-Tab or SHIFT-ALT-Tab I can see most of the Windows I have open, and can get to the one I want quickly. The last thing I want is some algorithm showing me a next/previous window that may have nothing to do with where I'm headed. How would I be able to predict where it would send me so I can reliably know how many key presses I need to make to get there?