LED chaser using as few wires as possible
You could do it with three wires (power, ground and signal) and a set of MCU's. You have one master node which send data out of the UART TX pin. The others all pick it up at their RX pin. You make a 2-byte protocol. e.g. first byte always has MS bit set which indicates an address giving you 128 slaves to talk to. Second byte has MS bit clear which is the LED pattern to output giving you control of 7 LEDs per MCU. You may need to boost the output of the master TX with a good driver IC but that depends on your baudrate. 



Just though of an alternative: chain the MCU's up. The first one picks up the data and re-transmit it at it's tx if it is not for him. This makes that each MCU needs to talk only to the next one: lower driver strength. Note that both schemes give you more then a simple LED chaser as you can make any pattern you want.