What is your favorite roofing smart phone app

I am interested to see what everyone’s favorite phone app is for roofing?

I’ve not seen any of them that are that useful if you’re interested in doing accurate quotes. If you’re serious about being mobile, buy one of the ultra thin PC Laptops and equip it with an air card (or if you have the latest smart phone with 4G/LTE and the right program with Verizon, make the phone a hot spot and enjoy 10 Mbyte plus download speed and 5 Mbyte plus upload).