I used servo motors, ultrasonic sensors and the ISD2560 etc to make some of my props and robotic items come to life.
Here is where I describe the electronics and code I used.
To turn the head of my Mini-Me Dalek I used a servo motor and a Picaxe 08
To sense when to turn the servo motor to move the head I used a Picaxe 28x and 3x ultrasonic SRF05 detectors details here.
There are slicker ways to add sound but these chips are still out there.