Here is a large 7-segment LED display for general score keeping. This project uses the Atmel AVR ATmega8 clocked at 8MHz. The two large 100mm 7-segment LEDs are multiplexed and controlled with 8 mosfets to increase the output current of the avr. The score is controlled by 2 buttons on-top of the black aluminum case (cool) which have different action to short or long press, or through an IR receiver. It has also a sound indication that can produce different sounds according to the waveform that is loaded to the chip. The audio sognal is amplified with the TDA2822. The whole construction is powered with 4 AA battery cells and can run for 3 hours. More info in this link.