Wikipedia - Wikipedia is a free online encyclopedia, created and edited by volunteers around the world and hosted by the Wikimedia Foundation.
Endless - Random and amazing Wikipedia articles.
Miraheze - Miraheze is a wiki farm (hosts wikis) for free and with no ads, it also provides custom domains...
Qwiki - Find and Read Articles on Wikipedia from your Mac menu bar!
Kiwix - Kiwix enables you to have the whole Wikipedia at hand wherever you go!
WikiPrank - Prank your friends with fake wiki articles.