I found a cool GPS navigation app that works on the iPad.
It's called Waze. In addition to turn by turn navigation, you can get real time traffic, accident, speedtrap information.
It's a "social network" type application. As people drive along using the app, it tracks your speed so that it can update other drivers. You can also report events, such as accidents and road hazards, so that other drivers, using the app will know about them.
The more people on the network, using the app, the better the app becomes.
The app also works on the iPhone, and they have apps for Android and Blackberry.