Schoology is an online course management system for individual and school-wide use. Schoology offers an online place to create assignments, post assignments, collect assignments, converse with students, track attendance, and maintain a gradebook. Schoology also offers teachers a platform for creating a course blog. The premium features of Schoology, which include layered privacy settings and student account management, are currently being offered to teachers (individual license, not school-wide) for free. If you sign up now, Schoology says that you will always have access to the premium features at no cost.

Applications for Education
I have not used Schoology with my own classes (my district mandates the use of Infinite Campus), but it does look like it could be a good system for teachers whose schools do not offer an online course management system.