I'm ready to merge Brian's histogram of gradient code. In order to remove the PIL dependency, I've added a new submodule called "scikits.image.draw", with Bresenheim's algorithm (used to determine the coordinates for plotting a line [or circle--not implemented]).
Please have a look and send any comments my way. I'll merge this tomorrow if I don't hear anything back.
Also, I think the new draw module could be a fun place for people who are new to the project to make a good contribution. For example, I'd like to see a NumPy implementation of Wu's algorithm for drawing lines and circles.