The TacType (iKeyboard) solves the one problem with a tablet computer—the impossibility of touch-typing on its virtual keyboard.
You can’t touch-type because a virtual keyboard (which is just an image on the tablet’s touch-screen) deprives you of the positioning cues and tactile feedback provided by a “real,” or physical, keyboard.
A touch-screen is super-sensitive, so it’s impossible for you to lightly rest your fingers on the virtual keys without typing the characters. And because the keys themselves are just images, you can’t know by feel alone where your fingers are on the keyboard.
More information: http://www.infogrip.com/ikeyboard.html