I am taking a programming class right now and I was thinking of building this as a small project.
It will be a visual user friendly program.
You will enter the rpm of the motor and the standard torque at max power. (Vex provides this info on each motor) This way you can also use non vex motors in this program.
It will ask for the number of teeth on each gear in the system. (It will be able to do say a 10 gear system)
The output will calculate the rpm, mph and km/h of the gear, and torque.
I know they are simple calculations but the program will do it in a flash no math required.