Check the GPS and Maps section. There is a sticky at the top that details all of the better known map applications.
With no data plan, you are much better off getting a stand alone GPS device, rather than trying to use one on your phone.
Most map applications download data and maps as you move and that cannot be stored on the device itself. There are a couple that can be downloaded and you can purchase a Garmin version, but again, given the costs, go buy a stand alone unit.