Since I am a genuine astro-geek, I have several pieces of software that I use in the course of my observing and education efforts. One of the best products I’ve run across is Stellarium.
Stellarium is planetarium software which is open-source. It is available for Linux, Windows, and Mac, and is currently at Rev 0.9.1. I have been using it for over a year now on my laptop during star parties and in classrooms.
Stellarium starts with a very uncluttered interface, using some buttons across the bottom to control most features. There are some features that are not controlled by the buttons, and you’ll have to learn the keystrokes for them.
Astronomy programs like “Starry Night” or “The Sky” may have more features, but Stellarium has a very rich feature set, and you can download it for free.