So you have a GPS, yes?
So you use maps online, such as Google, Yahoo etc.?
So did you know that there are copyright limitations on the use of those maps? How about public domain mapping? As a keen user of ForeFlight on my iPhone I read that they make use of map tiles from the Open Street Map (OSM) project. This is similar to a wiki, but allows anyone to contribute to the map, adding features, called nodes.
You can use your GPS to record tracks, then pop them onto the map adding information such as street names etc. You can add amenities, points of interest, just about anything.
Check out the map, have a read, and if you're a geek like me, join the fun!
Check out my Open Street Map Page and follow the links there.
If you'd like an excellent application to make use of your iPhone, check out lLOE - iPhone Little OSM Editor
And if you'd like an example of a node I uploaded using the iPhone iLOE app, click here