Browsing the show floor at Macworld|iWorld I found the SMK-Link Bluetooth Calculator Keypad. (Amazon Link) This Keypad caught my attention because I've always been a fan of the minimalist desk and wanted to use the Apple Wireless Keyboard but never could because of the lack of a numeric pad. The Bluetooth Calculator Keypad looks to solve that problem and more. It's a bluetooth numeric pad that will attach to the Apple Wireless Keyboard magnetically. It also serves a secondary function of being a standalone calculator, and a good looking one at that. There's a key on the device that will toggle between modes.
I've heard of devices like this before but this was the first opportunity I had to lay hands on one. Touch typists may find it somewhat frustrating that the layout of the keys is different than on a standard numeric keypad, but I would imagine this is something you would get use to over time. I did find alternative products including the Canon Wireless Keypad Calculator and the Cropmark LMP Bluetooth Keypad. What I liked about this model is that it magnetically attached to the Apple Wireless Keyboard which seemed more ellegant than other units I've seen.
I haven't had an opportunity to use this device for more than a few minutes in the booth, but a fair warning, all the units I looked at came with mixed reviews due to concerns over build quality, bluetooth pairing and longevity. I really like this concept but perhaps it's an idea that's difficult to implement well. The better solution may be to look at an alternate keyboard such as the Logitech Wireless Solar Keyboard for Mac that incorporates a slim design with a numeric pad.