From Kirk Hammett's KHDK stable, the Scuzz Box offers two very different modes (Fuzz and Scuzz).
Fuzz is much like any germanium fuzz (think Hendrix-era Fuzz Face), giving great dynamic tones that clean up nicely with your guitar's volume, while the tone and deep knobs act more as high- and low-cuts respectively.
Where it really comes into its own however, is on the Scuzz setting. This gives you a gated velcro fuzz tone with hint of octave/bit-crushed effects, but never becomes thin and grating in the top-end like some more extreme fuzzes can.
There's also a buffer switch that's really handy for reducing interference when used in conjunction with other pedals or long cables.