When I was in high school, I took a class in photography. It was one of my favorite classes, and I had a lot of fun with it. One of the projects we had to do was of course, the classic pinhole camera. Masking tape, tin foil, and an empty Quaker Oats carton make up the camera, then you expose directly on to a sheet of photo paper. This results in a negative, which you then use to do a contact exposure to another sheet of paper. The end result looks something like this:
This was my best shot at a pinhole exposure, and the one I turned in for a grade. The distorted perspective is an artifact of the paper being curled in to a cylindrical tube. With an effective aperture of somewhere in the neighborhood of f/200, exposure times on these cameras are on the order of minutes, so hand held is obviously out of the question. No need to focus though, as depth of field is practically infinite.
Pinholes are still popular. You can even buy pinhole "lenses" for modern digital cameras, which consist of essentially a body cap with a tiny hole in the center. You can of course make your own too.