I made one today although I was a bit lazy and just stepped out my front door and put a 0.5mm pinhole lensboard in my Deardorff 8x10. Using a tape measure it was roughly a 180mm focal length. Film was HP5 exposed for (1 mississippi, 2 mississippi) about 2 seconds and developed in Thornton 2-bath developer. What I find most remarkable is how precise the composition is considering I simply pointed the camera roughly in what I thought the right direction should be. No previews, bubbles or spirit levels. Maybe I should try being "lucky" a bit more often!
p.s. just checked the Worldwide Pinhole website and found one I did back in 2004 also on April 25.
p.p.s 2010 version now loaded also: