A Genuine Touch-Based Desktop
Touch would work just fine if your entire desktop -- not the computer-screen image, but your actual, honest-to-god top of your desk -- was itself a touch-sensitive display screen. I'm thinking here of the original Tron movie, where the boss had this nice big, fancy desk where computer images would appear on it (including the full-size keyboard). In the real world, you might want a desktop that tilted to 45 degrees, though.
But what I'd really like to see is a command-line interface capable of understanding whatever you typed in. If it couldn't understand you, it would ask in plain, simple, obvious language. Then it would remember, so in the end you'd be using your own personal shortcuts every day. The bonus here is that nobody else could use your computer under your login, because after a while, the server would be able to tell the difference between your warped mind and someone else's. There are times when I find typing things into a command line a whole lot easier than figuring out a bunch of @#&%#* little pictures and non-intuitive finger swipes.