2D Maps, 3D Maps old maps, new maps, satellite maps and every other type of map we have out there. We are living in a time of massively heightened sense of geographic awareness. with this new found need to use and see maps geocoding and referencing is becoming more necessary.
Here is a nice look up database running under the creative commons licence http://www.geonames.org/.
Here is the documentations http://www.geonames.org/export/ws-overview.html the api supports xml and JASON so it should work with any web-enabled technology.