My personal favorite is MapOut for the iPhone. Like many other apps, it has off-line vector map support, but it has the unique feature to create routes interac

My personal favorite is MapOut for the iPhone. Like many other apps, it has off-line vector map support, but it has the unique feature to create routes interactively by swiping your finger over the trail that you want to ride, and it will immediately build an elevation profile. It's incredibly useful when you didn't plan your route up front and you want to get an idea about what's ahead.