This stellar planetarium in your pocket is an application called Star Walk, and it’s only 99 cents on the iPhone, this is normally $2.99 and worth it for the price (the cheapest I’ve ever seen). It’s also available for the iPad for $1.99 (which is much cheaper than the usual $4.99).
I did a much longer Star Walk review a year ago with many screen captures and a lot more information that you’ll have to read for all the details.
This is a planetarium in your pocket. If you device has a the GPS and gyroscope, you just tilt it up at the sky and it will identify what you’re point it. It’s awesome! There are some similar products, but I think this might be the most polished.
Other than some small bits of information (and the space image of the day) you DO not need to be connected to the internet to use this information. So this is useful anywhere you can see the stars!!!