One of the neat things some of the Garmin Nuvis and Magellean GPS units have (maybe others too) is you can download a POI (Points of Interest) database.
There are literally thousands of POI databases; you name it. I have found everything from a list of West Marine stores in the US, to E85 gas station locations, to Hampton Inns. There are some databases available for a few states for boat launches, state parks, and even Starbucks!
And how about a database identifying intersections that have speed or red light cameras? How cool is that?
Most, if not all of the POIs are free, and many are done by corporate offices of the company that is in the database, state offices, or even individuals.
There are several places where you can get the POI databases; here is the one I use:
http://www.poi-factory.com/You have to download a POI downloader from Garmin, and optionally a POI creator if you want to make your own databases. Both are free from Garmin.
I think this feature tremendously increases the usefulness of the unit, so much so that it becomes a neat instrument to use locally (say you are looking for a particular resturant) rather than just during travel.