I'm trying to think of something where I'd need more computing power in my pocket - most apps seem to either have enough power in the device itself or draw the extra needed compute/storage from the cloud... just wondering what you have in mind.
I'm saying that many things you own would work better if they had a little computing power in them, or if they had access to a computer. So, for instance, it would be too expensive to put a PID controller in your toaster oven. That's why there's a simple thermostat and a simple timer in there. But imagine if your toaster could send temperature data in a bluetooth-esque way to your tablet. The tablet does the proportional-integral-derivative calculations and sends commands back to the toaster. So you get all of the benefits of PID controlled temperature without the cost of the PID controller.
Another idea (likely in the works somewhere): tablet as guitar effects pedal.
Interesting thought. I don't know anything about PID controllers - are they so compute intensive that they need a processor significantly more expensive than a Bluetooth controller?
On the guitar effects pedal: Apple has actually run an iPad ad that included a shot of a guitar plugged into an iPad running an "amplifier emulator" (not sure what the right term is for that sort of thing). Not sure which app it is, but it's probably $10 or less. :)