I had to install a Panel PC in a Clean-room last week where computer keyboards and mouse were not allowed. In order to allow my client to enter data into the database I was building for them, I had to create a Touchscreen Keypad inside Brilliant Database.
Some forms needed a Numeric keypad, and others needed a full QWERTY interface but the concept is all the same. Attached is a basic demo of how to do this for those interested.
Generally speaking, this method of input is great in most situations. Doesn't have to be a clean-room. Personally I will probably push my clients more towards touch screens now as this kind of input will suite them more.