It's OK to admit it — typing on a digital keyboard just doesn't give the same tactile satisfaction as on a real one. The Kiano4 does because it's a real sliding keyboard, rather than flipping, that attaches to your iPhone.
The keyboard rests against the iPhone's rear panel, adding just over a half inch (15.3mm) of width and 57g of weight. It connects via Bluetooth. The Li-ion battery holds enough juice for five hours of continuous typing and 30 hours on standby. Available in either black or white and compatible with iOS 4.1 and above, the Kiano4 will set you back $US100. [iNature]
The Kiano 4 in white
The Kiano 4 in black