Remote (RF or IR) control of DC motor
Any common IR or RF Receiver, a microcontroller to parse the signals, and a H-Bridge Driver. An H-Bridge provides a electrical motor direction control, instead of mechanical direction control based on a DPDT switch.

Alternatively, a DPDT Relay could be used. An H-Bridge would be better, in terms of Size, Speed (for PWM or electronic speed control), and Power Consumption, but a relay would be simple enough for regular on/off direction control. A microcontroller would need a simple transistor/mosfet driving circuit to control the relay.

General idea: