Darrell Tam has released DtBlkFx, an FFT based VST effect plug-in for Windows. It combines elements of distortion, filtering and synthesis and has an easy to use interface and lets you do all kinds of things, such as:

• 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.