Pharos GPS is an onboard program that works very well. I've been using it for quite some time.
Another good set of options are CoPilot live (you must use your data plan to download maps, but then they are on your storage card).
and iGo8, which is fully loaded onto your storage card.
Must say though, Pharos & CoPilot are my favorites. They both use a very read friendly map and are easily accessed.
CoPilot is currently on SALE for under $10 (
Give the Gift of Navigation this Christmas: ALK Technologies)