MapQuest: Maps, GPS, Voice Navigation & Traffic Not only is Mapquest free, but it's recently been updated to support background voice navigation. You can also view restaurants, gas stations, coffee shops, etc. It also supports basic voice navigation, meaning it will tell you when to turn, unlike the built-in maps app.
HoppinBill
MotionX GPS Drive is a really good, inexpensive GPS. Cheaper than TomTom and my experience with it has been excellent so far. The only time it ever led me astray was when I tried to go to a new store. It had the wrong address. But I emailed the creators and they updated that location quick-smart.
Associated Apps: MotionX GPS Drive