I'm using a board that outputs 3.3v and I have a small coin cell vibration motor (Vibration Motor - ROB-08449 - SparkFun Electronics). What resistor / diode combo should I use for this at 3.3v?
Its rated at a maximum current of 85mA and will run directly from 3.3V supply (if its
capable of 85mA). 1N4148 will do for a free-wheel diode, they handle 0.1A OK.
No resistor needed.
Note you cannot drive this directly from an Arduino pin.