Did some digging - and have found several voice modulators for arduino out there that can make you sound like you're a dalek. Some of them also do the lights control. Some mention the wave arduino shield from adafruit as a useful addition.

Didn't find exactly what I want (I'm more interested in one that can take playback rather than a microphone) but I did find that lots of things link to Project Dalek - looks like a really useful resource.