Stellarium
Anytime I am thinking about putting together a star party I have to do some research so that I can figure out some interesting things to look at. The sky is a big place after all, and there’s a lot of pretty lame things to look at. Also, “here’s a globular cluster that’s 4000 light-years away, with an estimated 3000 stars in it” is a lot more interesting than “ooo a cotton-ball blob!” when you are talking to people who aren’t so excited about astronomy. Or, if someone asks if you can see Neptune, it’s a lot nicer to say “Oh, it’s already set,” rather than “Hmm I don’t know where it is right now.”
I used to use the Sky and Telescope Interactive Sky Chart, but recently they changed it to require a user account, and even though the account is free, I don’t want to have one more account to remember. It’s just an extra hoop to jump through. So I looked around for some free star-chart software and I found Stellarium.
The neatest thing about Stellarium is that a lot of attention was given to visual appearance, and everything is rendered in true 3D with OpenGL. Sunrises and sunsets are rendered in a pretty realistic way, which is good if you want to get a feel for what is visible at a particular time. The band of the Milky Way is rendered for night displays, and the Small and Large Magellanic Clusters if you look from a location in the Southern Hemisphere. Constellations, including artwork, can be turned on as well. It was definitely an “ooh, ahh” moment, the first time I used it.
Anyway, if you are looking for a simple, free program for seeing what is in the sky, check it out. It’s quite nice.