Stellarium!

Celestia is a free real-time 3D space simulation, allowing unrestricted access to hundreds of thousands of stars.

Sky Map (formerly the Google Sky Map) turns your Android-powered mobile phone into a window on the night sky. Figure out what you're looking at:Point your phone at the sky, and Sky Map will show the stars, planets, constellations, and more to help you identify the celestial objects in view. You can also browse the skies in manual mode.

KStars is a Desktop Planetarium for KDE. It provides an accurate graphical simulation of the night sky, from any location on Earth, at any date and time. The display includes upto 100 million stars, 13,000 deep-sky objects,all 8 planets, the Sun and Moon, and thousands of comets and asteroids.

StarCalc is the fastest professional astronomy planetarium & star mapping program for Windows 9x/ME/NT/2000/XP (StarCalc version for PocketPC is available). It illustrates star positions of any instance of the day observed from any geographic locations on the Earth. The star positions can be viewed and presented as images of hemispherical whole sky or any of the user defined sub-areas. These images can be zoomed at different scales, rotated, screen-captured and printed. Also, StarCalc has many other functions of calculation and showing of sky objects. »

Stellarium Mobile is a fully-featured planetarium for your phone. It shows a realistic night sky map in 3D, just like what you see with the naked eye, binoculars or a telescope.

SkyORB is more than a simple star map, it's a collection of 7 tools including a 3D star map, 3D planetarium, ephemeris, search engine, sun clock, point to sky, weather, and more.

3D simulation of the Solar System and night sky - real time virtual orrery and observatory

The WorldWide Telescope (WWT) is a Web 2.0 visualization software environment that enables your computer to function as a virtual telescope, bringing together imagery from the best ground and space-based telescopes in the world for a seamless exploration of the universe.

Starmap is an intelligent sky navigation tool, written by a professional of the field.

Aciqra (uh-SEE-kruh) is a free and open source virtual sky map and planetarium which tracks and displays astronomical bodies including planets, nebulae and stars to an accuracy of a fraction of a degree for thousands of years into both the future and the past. It's software that generates a virtual sky so you'll know what's up in the real one.

Discover the fascinating relation between time and the cosmos. Enjoy this interactive learning tool and understand the concept of the celestial sphere and the apparent movement of the sky.

Gaia Sky is a real-time, 3D, astronomy visualisation software that runs on Windows, Linux and OS X. It is developed in the framework of ESA's Gaia mission to chart about 1 billion stars of our Galaxy in the Gaia group of the Astronomisches Rechen-Institut (ZAH, Universität Heidelberg).