I think it would be very useful if you create an App and a break-outboard where you have some digital/analog I/O .Some buttons and an textfield in these App showing the measurement on the analog input and the analog output from the accelerometer of the iDevice. And the Source code as Open source so everyone is able to adjust this app to fix his problems.
The Apple Developer Account is free and the iOS development tool are free too. very nice would be the availability in the Appstore but i don’t know what Apple is thinking about this and then it isn’t customizable. But it would be a big step into way to get more hardware using iOS.
