From the product page:
Sometimes digital is just TOO perfect. I’m not going to say “sterile” or “lacking soul”, because I’d wind up eating my words sooner or later…but sometimes you just want a little grit…a little dirt…a little imperfection. That’s where Bad Buss Mojo comes in. Bad Buss Mojo allows you to dial in specific tweaks to a virtual mix buss amplifier.
Bad Buss Mojo is available for Windows VST and costs $39 USD for a commercial use license for all hosts, and $25 USD for a Reaper-only, non-commercial use license.
Visit Stillwell Audio for more information and a link to download an evaluation version of Bad Buss Mojo.