Compute distance and bearing using Maidenhead location. This was originally intended for use by amateur radio operators who participate in microwave communications however it can be used by any ham in order to determine a distance and bearing to another radio amateur.
This version specifically for the iPad provides map and controls all on one screen. The larger map area over both iPhone versions should prove helpful. You get a map of the source and target along with a pin annotation and an overlay identifying the six-digit grid area. If a user touches an empty location on the screen for one second a new annotation is added at that spot identifying the grid. Any user-added annotations are removed if a new source or target are entered. This feature is great because you can zoom in on a location, touch the screen, and get a 6 digit grid; this is especially handy when your microwave buddy pulls over to the side of the road to make a contact with you (or someone else) but he/she has no idea what their grid square is.