Stellarium is a free open source planetarium for your computer. Stellarium renders 3D photo-realistic skies in real time with OpenGL. It displays stars, constellations, planets, nebulas and others things like ground, landscape, atmosphere, etc. It shows a realistic sky in 3D, just like what you see with the naked eye, binoculars or a telescope. It is being used in planetarium projectors. Just set your coordinates and go.
WWW: http://www.stellarium.org/