bentleg:
Gibb River was more than likely put in as a waypoint between Derby and Wyndham.
You're half right, I think. The GIB NDB was originally installed to service the navigation needs of DC3s involved in the Air Beef Scheme in the late 1940s, early 50s, before the Gibb River Rd was constructed.
Glenroy station at the time was one of the largest abatoirs in the region (if not Australia) and DC3s and Bristol Freighters used to land to uplift beef products to Wyndham port for onwards shipping to the southern states and internationally. The Gibb NDB was an enroute aid to facilitate navigation between Glenroy and Wyndam. Talking to some of the older pilots involved in the Air Beef Scheme, my impression was that there were numerous flight each day into/out of Glenroy Station at the time.