Work related…
Portal to the Heritage of Astronomy
UNESCO World Heritage Centre – Astronomy
IAU Working Group on Star Names

Other stuff…
International Astronomical Union (IAU)
Royal Astronomical Society (RAS)
SEAC (European society for Astronomy in culture)
Society for the History of Astronomy (SHA)
Society for the History of Alchemy and Chemistry (SHAC)
Austrian Society for Eighteenth Century Studies (ÖGE 18)


Random fascinating stuff…
Historical eclipse maps
100.000 stars (chromeexperiments)