Note: this post is from 2006, outbound links may be broken.
Christian Budde releases Christortion VST
Christian Budde has released Christortion VST, a freeware plug-in which excites the harmonics of the input signal.
It is also possible to invert the phase of each harmonic. This concept guarantees a very surgical control over the distortion produced.
Christortion is released as donationware.