We all now Google Sky Map and everyone wrote about it. But if you want something with even more polish and data, and especially for optimized for tablets, this might be for you. If you have a Samsung Galaxy Tab.
The app is available for free via the Samsung Apps store. A search in the normal Android market only shows a "non-hd" version of Star Chart which cost you, but nonetheless it's worth the money for normal screen sizes.
The graphics are brilliant, and if you tab on an object some information about it pops up. It has location and accelerator support, that means you can just point the device to the sky and see which star or planet you are looking at. Tab the sky and see more data. You can turn it off if you just want to do some research.
The important "Night Mode" for astronomers is also included, which make the colors all red. This will not disturb your eyes in the dark so much.
It's pretty basic, but it looks great and helps to identify a sky object immediately.
Looks like Samsung is beginning to put some useful stuff in their own market.