DtBlkFx (by Darrell Barrell) is a Fast-Fourier-Transform (FFT) based Virtual Sound Technology (VST) plug-in for use in audio software supporting such stuff.
It combines elements of distortion, filtering and synthesis in order to make you smile.
It has an easy to use interface and lets you do all kinds of things - examples are:
* Brick-wall (sharp roll off) filtering
* Harmonic based filtering
* Various types of noise control
* Frequency shifting
* Something similar to vocoding
* Many unique effects
DtBlkFx is freely distributable and is covered by the terms of the GNU licensing agreement. Source code is included.