There are many Web sites that include clickable maps that highlight regions on mouseover
and allow the user to narrow down a selection from a world map view to a continent level. Here is an interesting example: davidlynch.org.
Many of these clickable maps are implemented with HTML image maps, while another option is to use for example Google's GeoChart API. Concerning the HTML image maps option, I'm wondering where people get all the 'raw data', all the country and regional border polygons. Is there a free resource for that? Concerning the Google GeoChart option, I'm wondering if that is scalable or if the number of API calls are somehow limited?
Does anyone have some advice on the availability of a free library that allows a straightforward implementation of clickable maps with customizable regions?