I notice an unfamiliar form of magnetometer is
coming from the nanomachine shops: the xylophone magnetometer.
A current through a mechanically resonant bar results in a
deflection due the Lorentz force in the presence of a magnetic field.
The mechanical Q of the device provides a useful sensitivity
enhancement. Thought to have uses in sensing stray fields at close
quarters, say in noise reduction measures for outboard
magnetometers aboard spacecraft.