I have a couple apps for my Droid that really help me out when I am shooting long range.
The first is "Shooter", its a $10 app. This app gives you just about every bullet, weight and bc from every major bullet manufacturer.
The other I use alot is called "Range Card", this is a $5 app. It uses google earth and allows you to set points that will give you a straight line distance from point A to B.
Let hear what everyone else has downloaded on there cell phones for shooting.