If you do any backyard astronomy or have a telescope, this is a must-have app for your smart phone. It's Google Sky Map and it makes it a lot easier to find objects in the night sky on which to target your telescope.
When it's cold outside, I don't normally like to do this but in the Spring time (before the bugs are really bad) it's fun to take the telescope out into the yard and then use this app to find the planets and such.
It can be a lot of fun.
