If you are looking for a good smartphone app to estimate distance with a mil dot scope, try Reticle Ranger. I installed it on my DroidX and it works great. Free.
:~
I have it too.
Decent little calculator for quick estimates. Also does MOA and IPHY.
Mil-dot Master. nothing else even comes close.
Without a Scope, there is an App called "Spotter".
Uses the iPhone camera..you tell it the size of a known object in the view and it gives the range.
Free App
Mil-Dot rangefinder on the iPhone is nice. You don't have to type anything in. You use slide bars to input target size and mils. It also has a nice reticle view. It's free. So the price is right.
just found this and I'm really digging the mil app on the iphone. so I'm bumping this back up for anyone who may have missed it also. thanks op
Mil dot ballistics is really good