XOWA - The free, open-source, offline wiki application
Kiwix - Kiwix enables you to have the whole Wikipedia at hand wherever you go!
Evopedia - Evopedia is an offline Wikipedia viewer. Features: no Internet connection needed
Wikipedia - Wikipedia is a free online encyclopedia, created and edited by volunteers around the world and hosted by the Wikimedia Foundation.
WikiDroyd - Wikipedia is probably the single largest, most comprehensive and simply best information resource...
Aard Dictionary - Dictionary and offline Wikipedia reader.