Below is a list of sites which provide free educational content:
Khan's Academy - Contains many videos on a variety of different subjects including math, computer science, science, finance and economics, and humanities.
MIT OpenCourseWare - A free online university which has many courses available.
Open Yale Courses - Much like MIT OpenCourseWare, Yale offers free university courses
Know a site that provides free educational content? Then reply to this post and I'll add it to the list.