MOOCs, or Massive Open Online Courses, are structured, typically multi-week online courses.
You can search for GIS in Coursera. Coursera courses can be audited for free, including viewing lecture content. Not all features are available when auditing (e.g. quizzes will not be automatically graded, even the multiple choice ones). This is not an endorsement to pay for any Coursera content.
ESRI is offering MOOC styled content.