So you’re taking an astronomy class, or you’re a known astronomy enthusiast. You’ve probably already had friends and family ask you “Cool, so what’s that up in the sky?”.
If you happen to have a smartphone, there are cheap (often free) mobile astronomy apps that are basically pocket versions of Stellarium, with the bonus feature that they can display a “live” view of the sky that the device is pointing at.
There are tons of programs like this; I just looked for free ones with the “live sky” feature that displays a view of the sky “behind” the device. Apart from the Android apps Google Sky Map (very basic) and Star Chart (RA/DEC/constellation displays, fly to the planets and moons as long as you don’t mind that they all look like Ganymede), I haven’t actually tried any of these personally. I don’t know if they actually work, I don’t know what other features they have.
Google Sky Map (Free) https://play.google.com/store/apps/details?id=com.google.android.stardroid
Star Chart (Free as of 9/25/2013) https://play.google.com/store/apps/details?id=com.escapistgames.starchart
Stellarium Mobile ($2.00) https://play.google.com/store/apps/details?id=com.noctuasoftware.stellarium
Starmap Lite (Free): https://itunes.apple.com/us/app/starmap-lite/id505155967?mt=8
Star Chart (Free as of 9/25/2013) https://itunes.apple.com/us/app/star-chart/id345542655?mt=8
Star Walk ($3.00) https://itunes.apple.com/us/app/star-walk-5-stars-astronomy/id295430577?mt=8
SkySafari ($3.00) https://itunes.apple.com/us/app/skysafari-3/id437108143?mt=8
Windows Phone 7/8:
SkyMap Free (Free): http://www.windowsphone.com/en-us/store/app/skymap-free/d8d706b6-019e-e011-986b-78e7d1fa76f8
SkyORB (Free): http://www.windowsphone.com/en-us/store/app/skyorb/bca94fbf-61ae-4d3d-b86f-b973f0ecc23e
microsky (Free, but it may not work, and has no “live” mode): http://microsky.en.softonic.com/blackberry
no free app
StarTracker ($1.00): http://appworld.blackberry.com/webstore/content/20403462/
What’s up ($1.00): https://appworld.blackberry.com/webstore/content/48561/
Let me know if you know of any other good free ones.
Updated 9/25/2013: Apparently for the last seven months I’ve had bad links here. Fixed. Also, I added Star Chart to the Android and iOS lists because it’s free now.