Below is an example of a way to integrate an image map into collecting form data. One possible use for something like this would be to allow visitors to click on a part of a map to select their geographic location instead of making them select from a pulldown list. In a case like that you may want the form field that receives the value to be a hidden element, or you may not, depending on how you want your interface to work.
Another approach, if you really want to coordinates that the visitor clicked, would be to make the image an input element. (i.e., <img type="image" ... >) That way, the x- and y-coordinates of the place the person clicked get sent as the values elementName.x and elementName.y. To see this in action, click somewhere in the image below and then look at the URL in the location window once the page has reloaded.