If you have a Berry with built in GPS, you might be looking for free apps to make the most of it.
The one I use all the time is Google Maps. You can download it here: m.google.com. Its quick and accurate and the maps are very easy to read.
I've tried out a few other ones that have actual voice turn-by-turn directions. AmazeGPS is one of them. Download it here: http://www.amazegps.com/welcome.php It's pretty cool to have it talk to you, but the maps aren't very good at all and its not totally user friendly because it wasn't designed specifically for BB's. But it IS free.
Another cool GPS app I came across recently in App World is called, "GPSed: Track and Map Your Trips." It does exactly what it says it does. Read more about it here: GPSed.
Its very cool to see your exact location (in degrees), speed, elevation and direction of travel in real time. And even cooler that you can track your trips, save them and check it out later on your computer along with geotagged photos you took along the way.
Remember, you will not be visible to satellites inside. Although I have been spotted by Big Brother a few times before indoors. It usually works if you're close to a window and will almost always work outside. Obviously if its totally overcast, you're usually out of luck as well.
Anyway, try those apps out and let me know if you have any other ones you use.