Smoky joe:
a crude but genuine formant shifter, ie. makes voice big/small like a pitch shift, but keeps the same pitch. the only free formant shifter of any kind.
the technique i discovered that enables the formant shift can generate a lot of distortion, mainly on upwards shifts. to combat this, there is a 'smoothing' parameter and a low-pass filter before the pulse train (recognises zero crossings.) if you don't know what this means.. between the two, you should be able to get a fairly 'smooth' process (still little loops in silence and high frequencies like sibilance) but at the expense of hifi.. so ultimately more or less 'realaudio' quality audio, no mariah carey. mariah carey on a cellphone :p
however.. because of the glitch/loop artifacts, this vst has been praised for it's fsu capabilities ("this is great for drum loops") you can get some good performance out of it when shifting down, if you want to sound like jabba the hut - for shifting lower than the source, lower the 'skip' param (skips pulses, ie. at 2 only every other pulse, ie. better for 1 octave lower.. 4 pulses for 2 octaves lower..)
free vst plugin. pc
VSpectShift: basic spectrum shifter - you can shift the frequency bins inside an FFT buffer. (Note! the frequency shift is linear - whacky effects result - logarithmic would be more musical).
free vst plugin. pc
Madshifta: This new mad contraption does lo-fi pitch-shifting and mental feedback effects!! It even has midi control over the pitch shifting.
free vst plugin. pc, mac