Astro-Mania is an educational game covering the Universe. It has eight levels and let's you choose what subject area you want to cover. Its great pictures and ease of use makes it not only educational but also fun.
Downloads: 26350 - Shareware - Download Now

Accurate, flexible wireframe simulator for the Voyager and Giotto space missions, with animation capability. Developed at JPL for science/navigation, and filmed by the BBC/NOVA. Conveniently runs from any Windows/DOS.
Downloads: 45397 - Freeware - Download Now

Complete 2014 Nautical Almanac in pdf format complete with monthly star charts. Includes Parallax corrections for the planets which are not normally available.
Downloads: 28196 - Freeware - Download Now

Aciqra is a free and open source virtual planetarium and sky mapping program which tracks celestial bodies including planets, deep sky objects and stars.
Downloads: 49024 - Freeware - Download Now

Combine multiple sights on different tracks. Data available for 9999BC to 9999AD including a Star Atlas, twilights and eclipses. It will print conventional Nautical Almanac pages while the voyage plan is a sophisticated tool in its own right.
Downloads: 27954 - Shareware - Download Now