Has anyone tried the arduino with an accelerometer by feeding the axes into an opamp (like a LM324N) to amplify and stabilize a bit more the data going in? If so, do you notice much difference in the data with/without one? And if so, what resistance values are you putting on the gain and offset on opamp pins 1 & 2?
The LM324 like most other op amps does not have a gain pin. You set the gain with the value of the feedback resistor in combination with the values of the input resistors.
Putting a signal through an op amp will not stabilise a signal it will only make it a bit bigger.