You can turn on two leds throught 2 buttons.
If you press the first button the green led blinks and the buzzer beeps;
If you press the second button the red led blinks and the buzzer beeps like in the first case;
If you press all the buttons at the same time leds blink in a special way and the buzzer beeps twice ;)
It is an easy project and it is very costumizable, suitable for beginners.