Dave,

It seems like there is an answer in using several of the ideas mentioned. Using the PIC as your control device to since when you are speaking, a simple lm386 sound distortion circuit for your voice, and I would use a small cheap digital mp3 player for your sound(s). There are so many awsome sound effects free for the download... and the storage, sorting and interface platform is already built into the mp3 players.

Pop one apart, tie in a couple of wires and let the pic toggle through to the sound of your choice.

I did this with a CD player once. I programmed the pic to choose different wav files to play. It worked great.

And you can create your own sounds ... sans all the circuit hardware.

Ross