It's not an effect but fits the description fine i suppose.
http://www.whitenoiseaudio.com/doppelmangler/
# Timestretch, reverse, reorder and remix your sounds by visually redrawing their timeline.
# Change the rate and pitch of a sample independantly (higher pitched sounds no longer get shorter)
# Apply 20 different nondestructive MangleFX to the spectrum of the sound. These will let you do vocoding, frequency shifting and scaling, robotizing, hybridizing and more!
# Export and import .BMP's - Visually edit the spectrum of a sound in your favorite paint program!
# Morph between two sources.
# Work with any kind of sound - instruments, vocals, beats, etc.
# Utilize a full FX section - Phaser, Chorus/Flanger/Delay and Distortion/Wavewarper.
# Modulate your sounds using time-syncable envelopes that can also be used as LFO's
# Use up to 256 partials (partials are the basic compo nents of any sound) per voice