Globe at Night
http://www.globeatnight.org/
Hong Kong Night Sky Brightness Monitoring Network
http://nightsky.physics.hku.hk/
星空公団 (Hoshizora Kodan)
http://www.kodan.jp/
The BuioMetria Partecipativa project
http://www.pibinko.org/bmp2/?page_id=3218
Gateway to Astronaut Photography of Earth - NASA
http://eol.jsc.nasa.gov/
Cities at Night
http://www.citiesatnight.org/