Star Chart - Stellarium is a planetarium software that shows exactly what you see when you look up at the stars. It's easy to use, and free. Read more about Star Chart.
LunarSight - Accurate data about the Moon
Celestia - Real-time 3D visualization of space
Air Moon - Moon Phases AR - walking around and see how it occurs
Stellarium - Stellarium is a free open source planetarium for your computer.
Next Full Moon - All in one calendar to find the next full moon date