Francie Prose has written an interactive essay on the connection between madness and drawing. It's based on her viewing of an exhibit called Obsessive Drawing at New York's American Folk Art Museum. Her essay is nicely produced and nicely written, and manages to steer clear of some of the more cliched takes on outsider art. Instead of focusing on the psychology of the artists, Prose examines why art by non-professionals rose to the forefront at the same time that unabashedly commercial artists were being lionized by the art world. I found the drawing samples interesting, too, since most of the outsider art I've seen has been representational in some way or another, and this collection is mostly non-representational art.