New to 5.x, country_select module. This module makes use of the country/province data created for the addresses module to create country/province dropdowns for all countries in the world. Requires the activeselect module to work.
This module is a good solution for Drupal 5 users. Those wishing to have an address module in Drupal 6 might consider the location or addresses module. At this stage there is no Drupal 6 version of this module.
The 2.4 version has an option to save content in location module format. This provides location module upgrading provided you edit the nodes you want to upgrade.