The Google Ajax API playground (http://code.google.com/apis/ajax/playground/?exp=maps#map_markers) provides a nice exemple to add random markers to any map:
I'm creating a C# program that takes the users input as where they want to go and then based on that, it points them to a random location that matches their specifications.
"http://maps.google.com/maps/geo?q=29,-55" is the webpage that i'll use to determine if it's on land or not.. take a look at the specific "Accuracy: 0" string of the results of a page. If it's accuracy 0 then it's in the ocean. If it's 1 or higher then it's on land.