There are a lot of apps that can use it for little things, but the biggest thing the GPS is good for is Google Maps & navigation. I do a lot of computer work, including on-site repairs and setup. A number of times, when a customer makes an appointment, I will type their address into the entry on my calendar. Then when I go to drive to their location, I just open calendar, click on the address, and maps opens up. I click on navigation, prop the tablet up in its stand in my car, and have directions to their location.
It is good to know that Maps can't download map information without a wifi connection, but the GPS still works. So you'll want to set up maps of common areas to be available offline. Doing this a lot can eat up storage space, so if you plan to use your N7 for navigation much, buying the 32gb is probably a good idea (an area about the size of a county set to work offline will use 2-3mb of space). You also have the option, if you have a smartphone, to set up tethering so you have data on the go and can load maps on demand.