The Davis Mega Maze is excellent. It is an elaborate multi-acre corn maze, with bridges. It's a great deal of fun. If you're in Massachusetts, it's a worthy excursion each year, with kids, or as just adults. This year it took us over 3 hours to solve the maze.
Except when the battery performance is awful, or the on-device storage is running low I love my Android phone. The apps are fewer than the iPhone, but except for games, I find the Android apps more useful (Gmail, Gtalk, SkyView, Zombie Run, Barcode, Twidroid, WeatherBug, Calendar, etc.). In particular, My Tracks is really cool.
Put them together, and what do you get? An amazingly cool digital memento of this year's solving of the maze:
View Mega Maze in a larger map
In addition to the GPS resolution not being quite good enough to distinguish two paths in the corn that are barely a meter apart, they change the maze with non-corn barriers slightly every day, so it won't quite help you solve it, and it didn't help us that much when we were in the maze (though it did, a little), but it's really cool.