This is a small pedal I built some time back. It is wildly popular in the 'hi-gain' scene and most people agree that this pedal comes closest at producing the "MesaBoogie Dual rectifier" sound, on the cheap. There is still some serious bias adjustments to make so that worthy sound clips can be recorded. Building it is direct and relatively easy - things get difficult only in the biasing phase. I was not successful to achieve a good bias even after multiple attempts.
So here are some pictures, for now. I used gaussmarkov's layout(arguably the best) found on his site, gaussmarkov.net.
And here's the direct link to the article.
(I soldered the trimpots on the back, for easier access)
(This is the old pedal I salvaged for the casing)