Wikiversity is a Wikimedia Foundation project devoted to learning resources, learning projects, and research for use in all levels, types, and styles of education from pre-school to university, including professional training and informal learning. We invite teachers, students, and researchers to join us in creating open educational resources and collaborative learning communities.
Wikiversity
http://en.wikiversity.org/wiki/Wikiversity:Main_Page
no entrance requirements
no fees
everyone can take a course
everyone can create and revise teaching materials
anyone can participate in the learning activities
everyone can teach a course