Center for Archaeoastronomy - "Anthropology of astronomy": astronomical practices, celectial lore, mythologies, religions and world views of ancient cultures - University of Maryland
with the Public - IAU Division XII Commission 55: "It is the
responsibility of every practising astronomer to play some role in
explaining the interest and value of science to our real employers, the
taxpayers of the world."
Astronomy Facts - Star names, brightest & nearest stars, constellations, obsolete constellations, Solar System and Messier Objects; maintained by Shane Horvatin, Abrams Planetarium, Michigan State University
Astronomy Thesaurus - Click on the British flag to get started in English. One you select a term, you'll see it in French, German, Italian, and Spanish at the top of the page. Entries show Use, Use For, Broader Term, Narrower Term, Related Term (although most entries don't have all categories). There is also a hierarchical listing.
Birthday Stars - Looks for a star that is your age in light years from Earth
Encyclopedia of Astrobiology, Astronomy, and Spaceflight - "The goal is to provide a comprehensive source of information covering contemporary astronomy, astrobiology, and astrophysics, SETI, space missions, advanced propulsion concepts, historical aspects, and biographies (past and present)."
Journey through the Galaxy - "...a "mini-net" of pages that explores our solar system, stars, extra-solar planets, the theories about the past and future of the universe, and human exploration of space." Navagation is via the tabs at the top of each page.
physics.org - "The best physics resources, all in one place." hosted by Institute of Physics.