I measured across the pulley grooves on my TAIGs spindle with the belt in the grooves then subtracted .100x2 to get the effective pulley diameter to determine speeds.

pulley 1 diameter 2.060 circumference 6.472
pulley 2 diameter 1.815 circumference 5.702
pulley 3 diameter 1.520 circumference 4.775
pulley 4 diameter 1.225 circumference 3.849
pulley 5 diameter 0.930 circumference 2.922
pulley 6 diameter 0.580 circumference 1.822

speed for pulley 6 and pulley 1 is 11,544 rpm
speed for pulley 5 and pulley 2 is 6,342 rpm
speed for pulley 4 and pulley 3 is 4,032 rpm
speed for pulley 3 and pulley 4 is 2,619 rpm
speed for pulley 2 and pulley 5 is 1,665 rpm
speed for pulley 1 and pulley 6 is 915 rpm

MotorSpeed = 3250
SpindleSpeed = MotorSpeed * ( PulleyCircumference1 / PulleyCircumference2 )

How does a load meter work? Maybe something like this...

Motor rated speed is 3250, motor stalls when speed drops to under 2750 or at the very least the torque drops off rapidly at 2750. If the motor speeds from 3250 to 2750 were mapped to the values 0% to 130% to show the motors "load" wouldn't that be in effect a load meter?

2750 was just a guess for a cutoff rpm but would something like this be hard to make? A display mounted right on the motor just for something to look at to know when the motor is under heavy load or working with plenty of torque to spare. Sound is a good indicator but I like the numbers.

I would think an amp meter would be a better indicator. The motor maybe able to compensate for a load but it is still there. With an amp meter you can tell the load even if it's within the motors ability. You can then tell if a little more would push it over the edge.

Why not just put a tachometer on the spindle pulley. http://www.littlemachineshop.com/products/product_view.php?ProductID=1684