This is an idea I had a year or two ago. Basically take a powerful-enough computer and shrink it down to about the size of a cell phone. Make it really power-efficient. Only put a tiny battery in it (using external battery back for power). Don't put a display on it. Really it would be like a high-end cell phone without a display. People would simply keep it close (belt or whatever) just like they do their phone.
Have IO be wireless and go over a low-power, high-bandwidth signal that only extends out 3-6 feet (hence the bubble). This should be low enough power that it would not need to be regulated by the FCC. All peripheral functionality would be provided by external devices that communicate via the wireless. This includes touchscreens (ala phones), earpieces, keyboard, mouse. You could even have your watch tie in, or your car, or whatever.
The point is that you take your computer with you everywhere. The IO spec is open, so anyone can build any kind of peripheral they like.
Some neat things could happen result from this. For instance, you walk into the range of someone else's data bubble and suddenly you are able to be involved in certain transactions with that person. You sit down at your desk and suddenly your monitor comes to life with the output from your computer that is now in range.