Big Quick Keyboard - Free New Keyboard App Arrives in Android Market
The same arrangement as keyboards.
You can download free version from here.
You can download another version from here.
Try it. The big button is very easy to use. And this smartphone app is very, very easy to use.
If you put your thumbs future inside, you can touch more fast. Another easy method is that you can touch the upper side by your left hand and the under side by your right hand.