Not sure if this is the best place for this, but it's the forum I use the most so here goes:

I want to make my game a little more fun for my players by using voice changing software to emulate daemonic, servitor, or even just over-the-vox voices.  Does anyone know any good voice changer software I could use for this, preferably ones that will allow me to make my own patterns, rather than choose from presets?

For pre-recorded messages (that you could work on before the game) you could use Audacity. It's free to download and you could fiddle with the effects to achieve the sort of sound you want (slowing it down and lowering the tone could make it sound weird for a daemon, and you could add white noise or somesuch for vox).

It's quite easy to use, and you can export to wav (I believe) and mp3 if you get the plugin (and that's easy to do by following the instructions it provides).

I already have Audacity, but was looking for something more real-time. 

But thanks for the advice.  I may just try pre-recorded stuff in future. :)

http://www.screamingbee.com/product/MorphVOXJunior.aspx

This one works, and this version is free, but only has 3 voices.

http://www.youtube.com/watch?v=13t69RVq1YY&feature=related

this is a guy going through the full version(a trial of it) skip to 5 minutes for what your looking for.