Here is one company I think is rather unique, OhMiBod, but maybe there are other manufacturers with sound activated vibrators and vibrators that can be controlled by an iPhone App.

So my former pet looked into getting one so that when we had phone sex together she could literally get off on my voice as she could plug the vib into her phone along with a headset so we could talk and the vibrator would react to my voice.

http://www.ohmibod.com/products/index.php

There are also remote control vibs and eggs from this manufacturer but I have not tried the other products.