First, I should say that my LittleBits partners are a four-year old and two-year old.
This project started as a railroad crossing gate. It was very popular with the train set:
power --> slide dimmer -> servo
To upgrade, we uploaded some sounds (railroad crossing bells) from freesound.org onto an SD card. I left out the correct parts, and let the four-year old assemble an addition:
power -> split 1-> slide dimmer -> servo
split 2 -> button -> mp3 player -> proto -> synth speaker
There were other solutions, but this wasn't the first time we had this speaker/servo problem, so I appreciate the solution.
I'll try to upload some more of our creations elsewhere. None will win a beauty contest, but they get used a lot, and the four-year old loves building a toy with dad.