I don't understand why this is FREE... Boogex is unique, flexible, and sounds great.
Convolution simulation of numerous speaker cabinets: various diameter and number of cones, various microphone positions. This feature alone is priceless, and can be used "clean" if you turn the Drive knob down. The cabinets range from 6" practice amps to 15" bass/keyboard cabinets, and some of the mic positions are far enough out that you get room ambience (completely realistic thanks to the convolution technique).
Emphasis and Cut section lets you selectively distort specific frequency bands with a great visual interface. (The effect is pre-distortion EQ followed by the inverse EQ post-distortion.) This is extremely useful for controlling the distortion sound.
In addition there are conventional Lows/Mids/Highs EQ and Tone controls, adjustable Drive, Dynamics (compression I guess), Phase (?), and Out level. I couldn't find a manual for it but you don't really need it: move the controls and you'll hear what they're doing.
Boogex lets you dial in the exact tone you want, from fuzz to blues OD to metal lead, etc. Also great for bass, keyboards, etc. I would have paid $$ for this, but don't tell Voxengo! (I guess it's a good advertising gimmick because I ended up buying Elephant and Marquis from them.)