WikiArt (formerly known as WikiPaintings) is an online, user-editable visual art encyclopedia. Based upon a statement in its 2013 financial report, the site appears to be online since 2010. They claim to have reached 75,000 paintings as of June 2012. As of February 2013 "the Wiki functionality of the site is still under development". The developers are based in Ukraine.
References
WikiArt Wikipedia(Text) CC BY-SA