A planetarium software that shows a 3D simulation of the night sky
Stellarium renders 3D photo-realistic skies in real time with OpenGL. It displays stars, constellations, planets, nebulae and others things like ground, landscape, atmosphere, etc.
Fortran library to compute positions of celestial bodies
libTheSky is a Fortran library to compute positions of celestial bodies (Moon, planets, stars) and events (conjunctions, eclipses). It forms the core of the software that produces the Dutch popular-astronomy website http://hemel.waarnemen.com
Jewish prayer times
Android application that displays list of halachic/halakhic times for Jewish prayers (zmanim and zmanei tefillot).