What is a POI anyway?
A GPS POI or Point of Interest is nothing more than the location of a particular spot on the map. To be sure, a POI is a in a very specific format and this format may vary between the GPS units from various manufacturers.
For example a collection of POIs for my Garmin unit looks like this:
-77.29161, 39.19600, "Black Hill Regional Park"
-77.16684, 39.00939, "Cabin John Park at Bradley"
-77.16908, 38.99635, "Cabin John Park at River RD"
The first number in any row is the longitude, the second is the latitude, and the third is any label you might chose to give the POI. In this case, the POIs are parking spots for bicycle rides.
What do you do with POIs?
Most manufacturers provide some sort of mechanism for loading POIs into the unit. For example Garmin provides a free utility called a POI Loader. Click here for the download and more information.
Where can I find some useful POIs?
A Google Search will turn up hundreds of download sites, some free, some not. Some others I have found useful:
I have created some lists for my own biking and boating: