I am not a fan of external keyboards. I prefer using my notebook keyboard only. But this new keyboard has some very nice possibilities: http://www.engadget.com/tag/eee%20keyboard. E.g. calculator emulators that can have X sent to the PC application.
I've asked for this feature in i41CX and I'll also ask that Free42 for the iPhone also have this feature. There are keypad applications for the iPhone already. If the two ideas could be merged, then my iPhone could be my smart calc extension to my keyboard.