Citizendium, powered by MediaWiki, is "an open wiki project dedicated to creating a free, comprehensive, and reliable repository of structured knowledge". Unlike with Wikipedia, a contributor must register using their real name and verify their identity.
WikiExplorer is the most advanced Wikipedia reader app for Android devices, it presents Wikipedia articles in a clean and elegant interface, for your best reading experience.
Alchetron.com is a free social encyclopedia for world where you can create, organize and learn easily using topics.
With Alchetron you can search & share thousands of organized topics which can be biographies, free courses for students etc.
Wikipanion is the best and fastest Wikipedia browsing application for the iPhone. Wikipanion uses a direct connection to the Wikipedia servers, making it extremely fast. Never deal with overloaded third party servers. Never worry about third party server privacy concerns.
Wikipedia is probably the single largest, most comprehensive and simply best information resource out there on the Internet - a really great resource.many people though would like to have access to this giant resource when they're not plugged into the Internet.Discontinued
The official website is no longer available. Last version, 1.4.11, released on November 2011, can be still downloaded from Google Play Store.