Ignite Amps has released TS-999 SubScreamer. This free VST plugin is inspired on an overdrive pedal for metal guitarists.
SubScreamer can give a nice overdriven sound to audio material like a guitar or a TB-303 like synthesizer bassline, without sounding too harsh. A disadvantage of this plugin is the relative high cpu usage, which possibly can give problems with older computers.
SubScreamer is available for Windows. For more information and the download location visit the KVR forum.