Due to the publicity and focus on Gravity Probe-B exp. over the last 20 -30 yrs., it is not commonly realized that other proposals have been made for the detection of gravitomagnetism.

For example, here is an interesting possibility put forth by Braginsky and Kip Thorne which uses a Foucault pendulum technique placed very close to the South Pole (earth's rotational axis).


In light of the trouble we're having with the Frame dragging aspects of GP- B, it might be worth a try.