Lots of commments on military applications, but bipedal robots are inferior to wheel vehicles, planes, and aerial drones, in terms of speed and maneuverability. Everyone's so afraid of Terminators hunting them down, when in reality, mostly invisible , and mostly silent, Predator drones from a mile away that will kill you with precisely targeted missiles should be your real fear. Or commercial quad-copters carrying an…
IIRC the humanoid Terminators in the movie are infiltrator units. Skynet will definitely have more conventional aircrafts and wheeled vehicles to hunt us down.
Similarly, Terminator 2 showed large tracked vehicles.