A freeware, no-frills "homage" to a commercial product.
A maximizing limiter type thing, you can slap it on your master channel and get instant OOMPH out of your tracks. Just choose one of the 4 EQ curve variants and dial the knob to adjust the intensity of the effect. While this may be a quick fix for works in progress to see how they shine up, you are more likely to get far better results from this plugin if you take the time to EQ and mix your tracks adequately.
ADDENDUM: Image Line's Maximus maximizing limiter plugin has four "Soundgoodizer" settings which are basically the same four settings of this plugin. So if you like this plugin, and you want more control over what it does and how it's doing it, get Maximus!!!