Freebo

Freebo is Topics search tool. If you don’t know something, ask Freebo, it probably knows.

Alchetron

Visit Alchetron it is a free social encyclopedia for Internet users where you can search & share thousands of organized topics which can be anything and everything !!

Citizendium

A wiki for providing free knowledge where authors use their real, verified names.

Daily Curiosity for iOS

The top 5 things to learn on Curiosity.com, delivered daily.

Wikiversity

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.

the full wiki