Teachable - Create and sell beautiful online courses with the platform used by the best online entrepreneurs to sell $100m+ to over 4 million students worldwide.
Sitecake - Drag and drop CMS for HTML websites. It's flat file CMS so it's pretty fast.
Clever - syncing between education applications for K-12 schools
Anchor CMS - Free and lightweight blogging system
Claroline - Claroline is a collaborative eLearning and eWorking platform.
Textpattern - Textpattern is an elegant content management system that is free, open source software.