On Classmill you can create public or private (invitation-only) courses. Courses are built as a series of modules. In each module you can include videos, text, images, links, and file attachments. You can also embed games and interactive simulations into each module. A discussion forum is automatically added to each module in your course. If you make your course private you will have to email invitations to your students.
Applications for Education
Classmill could be a good platform through which you build self-paced professional development courses. It could also be a good platform for building summer enrichment courses for middle school and high school students.