I made a little microchip circuit for my car that means I have:
- Headlights (150,000mcd LEDs - about as bright as a 30W light bulb)
- Front and rear turn indicators (work automatically when you turn)
- Reverse lights (when you reverse, they activate)
- Brake lights (when you brake)
- Tail lights (red)

When radio signal is lost, a failsafe activates, and all the lights turn off, except the indicators which flash.

A really great, simple circuit.

A