eLearning on WordPress: Comparing WP Courseware and LearnDash
Comparison of two Wordpress LMS/course management solutions: WP Courseware and LearnDash
Sensei | A Learning Managment System for WordPress | WooThemes
Wrodpress plugin with some basic LMS functionality. User registration, course and lesson creation, quizzes, tuition, analytics. No SCORM compatibility (although that's planned for the future).