There is a $0.99 (yes, exorbitant by pilot standards) app in the App Store called 737 approach speed that has saved my bacon several times with late, changing wind calls. I like that it has pictures and that I can set the runway heading and then drag the wind line to wherever, set velocity and gust, and voila, that quartering tailwind with mild gust at LAX is out of limits for landing. YMMV