These are all free Plug–Ins but you have to register their site.
– Bark Of Dog v1.2.1
– Mongoose v1.1.0
– Panipulator v2.0.1
Resonant high pass filter
Bark of Dog is a bass resonance filter that lets you increase your low end without turning up the flab. I like to think of it as a way to boost the low end while still keeping it under control. While the controls are super simple, the effect that this has on controlling the low end in a mix is pretty exciting.