I'm a big fan of Futurama, and if you are a fan too you will know that Leela (and some other non-regular customers) have a wrist-computer. It is seldom used in any plotlines, but it is not the only film or program that has the idea. Predator (although I realise the Predators interface was somewhat limiting!) or the even more extensive and futuristic

To me it makes sense - the wrist (and forearm) is a vast expanse of wasted space on your arm, why not use it?

As we tend towards a more digital lifestyle, more and more of us are carrying a PDA, a phone, an MP3 player. We hear about convergence of these items so that we only have to use one pocket, instead of three, to carry all these items.