The D*A*M Meathead has been used by many top guitarists - Josh Homme of Queens of the Stone Age is one. Taking that into account you can imagine what this thing sounds like - it's a massive fuzz tone! Here's a description from the D*A*M website:
"The Meathead. Often imitated, never surpassed. Little box, big idea. Caveman style fuzz tones for killing dinosaurs. Crank it up and hit that switch. Ka-pow! The flavour is thick and raw with a throaty woody bark. Optimum clarity and saturation are delivered with a long syrupy sustain at mountainous volumes. The bass to treble response is perfectly balanced for a heavy but dynamic fuzz tone that will project as well as it can saturate. A most excellently low background noise is achieved through careful transistor selection and biasing which further enforces the Meathead's fluid and articulate sonic capabilities."
And a demo video of the D*A*M Meathead in action:
Here's a schematic drawn by Analogguru:
As you can see it's the standard Fuzz Face setup with a few nice tweaks to smooth things out (those caps from the transistor collectors to base). Transistor selection makes a huge difference here, try different types for new tones.
And a veroboard layout by Mike:
And another great vero at IVIark's great site: http://tagboardeffects.blogspot.co.uk/2010/10/dam-meathead.html
And here's the de'luxe model "M-25":
And here's a vero layout from beedotman:
As you can see this version adds in a trim pit to allow the perfect bias to be dialled in and also a "filter" control which is a basically an input blend control which allows you to adjust the low end response of the circuit. The "attack" control is the standard fuzz face "fuzz" control and adjusts the overall gain of the circuit..
Here's the freestompboxes forum topic for reference: http://freestompboxes.org/viewtopic.php?f=7&t=2713