Occasionally, no matter how many times we told them, students would use a color print film accidentally and of course develop it in out D-76 (using the ASA and brand of film to figure out development times, I guess). They could make B&W prints, but not quite up to their B&W standards -- but they usually did not put in the effort, and re-photographed with the proper film and a lesson well learned. Experimenting with B&W development as koraks suggested, might yield interesting and usuable results.
Processed as color negatives, one could start to predict the effects on the colors in the scene as they translate onto color neg film, and use that to create one's images on B&W paper. Walls of graffiti might take on a stronger graphic feel, for example.