My favorite would have to be CoPilot Live. It's an amazing Offline GPS UI that uses a prepossessing map pack. Mine's the whole Southeast US. It's very accurate and user friendly. And best of all, free.
I use this on my Samsung Galaxy Tab 2 7.0. Love the huge screened Map.
Now, coming in second for me would be Textab. A Bluetooth SMS app texts are forwarded between Tablet and phone, so I can use a better larger Keyboard. It cost me $2.99. Well worth it though.