This is exactly what Canon did with the X Mark I Mouse, having announced it for a US release. This is a combination device that will feature a physical 10-digit button numeric keypad that connects via Bluetooth 2.0, making it the ideal notebook companion.
This hybrid input device will also see a trio of mouse buttons and laser tracking capability. It will retail for $60 when it arrives next month – which frankly, is not too far away. Color choices are rather limited though with just black and white, so I would opt for the former since you don’t see the dirt build up that fast.