TL:DR; Educational orbit and gravitation simulator for high school, college and beginning university physics and astronomy.
Download Orbit Xplorer Shareware - Rating: 3.84
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.
Complete 2014 Nautical Almanac in pdf format complete with monthly star charts. Includes Parallax corrections for the planets which are not normally available.
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.