A great app from google. Google Sky Map, an app similar to Stellarium which shows stars, planets, and moons in the celestial sphere.
You can know the star's name in the sky by just pointing your Android phone in the same place in the sky as where the star is. It will display on the screen the exact same stars in front of you. It makes star identification very easy. You can also activate constellation markers to identify the different constellations in the sky.
It also has a search function that will show you the exact location of a star in the sky by just following the arrow pointing in the screen.
The Google Sky Map is available free in the Android Market. :)