XOWA - The free, open-source, offline wiki application
Wikipedia - Wikipedia is a free online encyclopedia, created and edited by volunteers around the world and hosted by the Wikimedia Foundation.
Kiwix - Kiwix enables you to have the whole Wikipedia at hand wherever you go!
Daily Curiosity for iOS - The top 5 things to learn on Curiosity.com, delivered daily.
Evopedia - Evopedia is an offline Wikipedia viewer. Features: no Internet connection needed
Inquire by Tamper - The easiest way to discover the world around you.