Xponaut has released Voice Tweaker 4.1. With this new version of Voice Tweaker you can pan the processed and unprocessed signals individually, and utilize the new "Wave Hold" parameter for spectacular effects. Also, it has a completely redone user interface with a more logical and clean disposition of parameters.
For those new to Voice Tweaker, it is a high-quality, natural sounding VST and AU plug-in pitch shifter with the ability to transpose the pitch of a monophonic signal (a voice or an instrument) up to 2 octaves, up or down. No chipmunk or monster voices, unless you want to of course, because Voice Tweaker can also transpose the formant of the signal an equal amount of 2 octaves up or down.
Add to this a full fledged pitch correction(auto tune) section with MIDI control, advanced modulation matrix, vibrato and you have a very versatile tool at your fingertips.