Coursekit is a free course management system (similar to Blackboard or Moodle) that is described as being more "social". It was developed by recent graduates who wanted to change how students and instructors interacted outside of the classroom. It has already gotten some rave reviews and is being used by thousands of instructors and students already.
Coursekit combines a variety of tools for educators to use for extending their classroom or even creating an online course. Discussion groups, assignments with grading, resource sharing, a class calendar, and a community forum are just some of the tools available. Educators can post links, videos, and other files, hold online discussions, and even write a blog post.
It's one more tool educators can use to connect with their students outside of the classroom.
LearnBoost - free online grade book and lesson planner and more
MyBigCampus - course management system - follow my year long review of it on Tech&Learning.