I've been playing around with a Lego Mindstorms NXT robot, gearing it for speed and power. To my dismay, when geared for power, it wasn't any harder to stop than when geared for speed -- I suspect that it doesn't have very good traction (as there really isn't much mass pushing down on the wheels).
It would be nice to be able make quantitative statements about how much force (and thus, how much torque) a robot puts out. Does anyone know how I can do this? Would, for example, a spring scale or force gauge work well for this purpose, and if so, what is a good maximum rating to look for?