MAKE group member Leevonk has a great Instructable on franken-modding a Furby… he writes -

“I took control of a furby’s body using a PIC16F877 microcomputer. Videos on last step.

The furby’s in-built sensors and actuators:

light sensor,
IR sensor,
IR transmitter,
tongue touch sensor,
belly touch sensor,
microphone,
speaker.

The furby’s main (and only) motor was dead, so I added other motors.” – Link.

Related:

• Circuit bent Furby – Link.
• Furby goes Godzilla – video… – Link.
• New Furby Hacking : Part 1 : Skinning… – Link.