Taiga Gravel

Taiga DSP releases Gravel, a freeware bitcrusher/distortion effect with a built-in envelope follower.
The plugin offers three different types of distortion (drive, bitcrushing and sample rate reduction), paired up with an envelope follower module. The combination of a distortion effect and an envelope follower can result in a wide variety of effects, ranging from simple bitcrushing and analog style distortion to subtle transient treatment, compression and all sorts of heavy audio mangling.

http://www.taigadsp.com/gravel/