Fuzz and Distortion Effects

A fuzz, overdrive or distortion is perhaps the first thing that comes to mind when people think about guitar effects and for many it is their first pedal. I dare say that for most it really is their first effect as most amplifiers do some form of this.

Links

Sites with multiple fuzz and distortion circuits

Beavis Audio Research - Four Knob Rat, Fuzz Lab Jr, ScreamerLab, Trotsky Drive, Valve Caster.
Tonepad - Ampeg Scrambler, AMZ Overdrive Pro, Big Muff Pi, Blue Clipper, Blues Breaker, Boss DS-1, DOD 250 Distortion, Easy Face, Fuzz Face, Guvnor, MXR Distortion Plus, Rat, Sans Amp GT-2, Tone Bender MKII, Tonebender 3 Knob, Tube Screamer, Tube Sound Fuzz.
Run Off Grove - Double D, Eighteen, The English Channel, Flipster, Grace/Big Daddy, Matchbox, Mockman, Peppermill, Professor Tweed, Supreaux Deux, Thor, 22/7, Tube Reamer, Umble, Uno.

Non tube

Big Bastard - Also known as Big B*****d, high gain.
Big Daddys Bastard Sister - Related to Big Bastard.
Big Muff - Classic(ish) fuzz in multiple variants.
Dr. Boogie
Fuzz Face - Legendary fuzz circuit.
Fuzzrite - Another legendary fuzz circuit.
Proco Rat Distortion - Veroboard layout.
Professor Tweed - JFET tube emulation goodie from ROG.
Pushme Pullyou - Octave fuzz.
Rump Roast - Can also be wired as a booster.
Spitfire
Suzy Q Harmonic Clipper - Adaption of a Kustom amp channel by (Pink) Jimi Photon.
ToneBender

Tube

Matsumins Valve Caster - Tube boost and light overdrive.
Spark Gap - Tube Screamer with tubes!
Tube Star - More gain that Matsumin
Shaka SubCaster - Shaka Tube with submini tube, thread also has information about Shaka Tube.