Hi there LMR, here is another one of our projects, as promised. :)
This is Xylomatron. It is a robot that you can play a game similar to "Simon Says" but with a xylophone interface. Basically, it does play a note and expect you to repeat it, if you succeed it adds another note to the previous sequence and expect you to do the same. Therefore the game gets harder at each level, depending on your memory.
When you fail, it gets quite angry thinking "The puny human couldn't memorize X notes" (it does really trace it in fact :D)
To detect the notes, it uses 2 digital pins, each attached to 4 different value of resistances with a pull up circuit. The user closes the circuit using the stick, therefore returning a specific value. This method seems to need lots of trimming over time, the values change, to cover this issue we have coded a trimming function to the robot.
Although, we will soon print a board and change this method with a more solid shift register solution, which actually we couldn't do at the time because of the lack of the component on the night we were finalizing its prototype circuit. We were caffeinated, sleepy, I really don't know what we were thinking by adding the pull up circuits.
Anyway, the robot has 6 servos. 4 mini servo is on the arms and 2 micro servo is used for the neck. We have used an ardweeny (a quite cheap and small arduino clone) to run it.
The entire hull is hand-made and painted, used a pvc-foam called sintra.
Here are some photos from development (click to enlarge):