I have a course under development, and I wanted to be able to test it from a student's perspective, so I set the course to be open to students. I didn't want to open the course to students, but the only way I could create a student account and make it work was to have the course open. I have not set my site to have any page with the courses publicly listed. I only have one course that is supposed to be public, to which there is a link directly from the home page. I was browsing my logs this morning and discovered four people had enrolled in my course under development. While the course was open, I looked at their logs, and for the life of me can't figure out how they found the course. They did not reach it from a page that linked to it, they seemed to just have gone from login to being in the course. I've put an enrollment key on the course now and booted the people out, but there is something funny going on here.