MotionX GPS is a full-featured GPS app for your iPhone or iPad (it's also optimized for the iPhone 5). Use this app to see your position on a NOAA chart, topographic map, or road map, get your bearings in true or magnetic, visualize your progress and ETA, save your waypoints, and share your location with friends via email or Facebook. This is a handy app for any outdoor activity—hiking, biking, climbing, and, yes, sailing—and has some pretty cool features for each. Check it out!
Available at the iTunes App Store; $0.99.