For my object recognition class, I wrote a corner detector and an edge detector in Python. All of these programs require the free version of the Python Imaging Library, which is NOT included in my downloadable archives.
I think the edge detector works better than the corner detector. That is to say, the edge detector seems to be much better at detecting edges than the corner detector is at detecting corners.
I also implemented some cool algorithms in Dr. Nishino's computer vision class, but I don't want to post them here because he still teaches the class. You can see the results here (coming soon!).
I wrote a text-based version of the popular game Battleship in three different languages. I can't find the python version, but here are the other two. I used clisp, and the standard Pike interpreter to run them.