If you think typing on the flat touchscreen surface of your iPhone gives you no sense of typing, then you should dress your iPhone with iTwinge. This device is believed to be the first physical QWERTY keyboard to give your the tactile feedback like the usual mini sized keyboard.
Produced by Mobile Mechatronics, iTwinge is a detachable keyboard which you can just slip in and out in seconds matter. Just one downside though, if you have dressed your iPhone with dedicated case, you would have to remove them before you can actually put iTwinge on.
iTwinge keyboard will cost you $29.99 to own one and it’s compatible with both iPhone 3G and 3GS.