Garmin introduced their Tour Guide feature on the Nuvi's over a year ago. Most new GPS display JPGs, play audio in MP3 format, and handle proximity alerts, and the new(ish) zumo even captures screen shots as JPGs. The only issue with Vince's application is the scale - the locations may be very close toghether - perhaps closer than the GPS basic accuracy.
Here's what Garmin says about it's Tour Guide Feature:
What is Garmin TourGuide™?
With the latest POI Loader software, third-party developers can create and load special Garmin TourGuide POIs, which turn your compatible Garmin unit into your own personal, electronic tour guide. These POIs have an MP3 audio file associated with them. When you pass by a TourGuide POI with your compatible Garmin unit (must have MP3 playback capability), the TourGuide audio file begins playing automatically. Garmin TourGuide has so many different applications: you can use it for bus tours, hotels, rentals, real estate sales — the possibilities are endless!
Garmin TourGuide POIs are currently compatible with nüvis® with MP3 playback capability, zūmo™, and the StreetPilot® c550, 2730, 2820, 7200 and 7500.
Creating TourGuide Files
TourGuide is a feature available on compatible Garmin devices. TourGuide files include Custom POIs with descriptive .mp3 audio files. When you approach a TourGuide point, the .mp3 file plays and provides you with information about that point, much like a guided tour. TourGuide files must be saved as .gpx files.
NOTE: TourGuide files are usually created by third party developers.
To create TourGuide points, follow the steps for creating Creating Custom POIs in MapSource and use the File/URL field to attach the appropriate .mp3 files to the points. The .mp3s must contain the word “TourGuide” in the file name to activate the TourGuide feature. For example, “TourGuide.mp3”, “TourGuide USA.mp3”, or “TourGuide 12.mp3” are all valid TourGuide file names.
After you have created all your TourGuide points, save them as a .gpx file. See Creating Custom POIs in MapSource for more information.
After you have saved your TourGuide points in a .gpx file, you can save them on an SD card or load them on your compatible GPS unit using Express Mode or Manual Mode.
Adding Pictures to TourGuide Points
You can add .jpg images to your TourGuide points by following the steps for creating Creating Custom POIs in MapSource. Save the .jpg images and TourGuide .mp3 files in a directory, then use the File/URL field to link to that directory.
You can also include the path to the .jpg image in the ID3 data of your TourGuide .mp3 file. Search the internet for more information on ID3 tags for .mp3 files.