There are free university courses being made available online by https://www.coursera.org/courses
Numerous universities in the states and Canada offer video courses, 8 to 10 weeks long, complete with quizzes and assignments. If you get 80%, you receive a certificate. I'm enrolled in two (but will have to drop one due to time constraints) and have another one starting in November. So far, I'm very impressed with the courses I've taken.
There are new ones starting all the time and last I checked the time-table was filled till May next year with other courses after that TBA. So there is likely something of interest for almost anyone in the courses.
Highly recommended for those wanting to keep brain rust at bay, learn something new, or just review a subject they're already familiar with. Plus it is fun. They even have discussion boards where you can chat with fellow students. As well, some courses have FB pages or separate links where they post other informative, educational sites related to that course.