Indeed I do. While it's one of the coolest things since sliced bread it does turn you into a compete idiot, much like speed dial on your phone.. "Hey Steve.. what's your Aunt's phone Number?" ...
"uhhh.. #12?"
I've got mine for work. I cover almost 200 cell sites for our PCS company so being able to track my position helps a great deal when looking for a unlit tower in the middle of the night with trees all around you and very cryptic directions in our site access log. We use standard Garmin GPS units with the data cable that allows you to hook them up to a laptop and track your position, plan routes realtime, etc using DeLorme's Street Atlas software.
I've also used it for some long road trips (Florida comes to mind) and being able to track addresses is nice as well. The setup is a bit large and cumbersome since you have to use a laptop to gain any real functionality. The smaller dash mounted "Street Map" units from Garmin are more gimmic than useful. Sure they can show you where you are and maybe even get you home after.. but for route planning and location finding they don't work well at all.
And after using mine for quite a while now I can tell you, that like anything else technological, you become dependent on them. Move me one block from the house I've lived in almost my whole life and I'm lucky if I can find my way home, under the noon sun, with a roadmap, directions and a guide dog without the damn thing.
If you have a legitimate use for one they can be quite helpful. If you're just looking for the latest bit of "wow", "cool", "Gee-whiz" bit of technology to stuff in your car I'd advise against it. You can spend the $300 better under the hood of your car! :smile: