The AV8B Harrier II has 4 rotatable main engine exhaust nozzles that can rotate slightly past 90 degrees, providing thrust for VTOL takeoff, as well as rotating horizontal for conventional flight.
There is a single engine feeding all four nozzles, though IIRC hot exhaust exits only the aft nozzles, while the front are cool air from the turbofans.
In addition, for yaw/pitch/roll control while hovering, there are reaction thrusters in the nose, tail, and wingtips that can push the plane about while it's balancing on the main nozzle thrust.
In addition, the Harrier is an *extremely* difficult plane to fly in hover. The original Harrier had something like a 1/5 fatality rate for the pilot training program. Much has been improved in the Harrier II, though a full fly-by-wire system would probably make the plane much safer yet.
Finally, the Harrier rarely utilizes true vertical take-off. It's much cheaper on fuel to use a short roll-out w/ a 45deg thrust vector. Plus it allows the plane to take off with a much heavier payload. And for the really heavy launches, there's the ski ramp:
/me used to be a big military aircraft nerd.