Varies somewhat
AFAICS I can get good info on US and UK stuff - there are separate teams for other markets. Much of the address validation stuff is simpy web based white pages (available by subscription).
[link|http://www.blackbagops.net|Black Bag Operations Log]
[link|http://www.objectiveclips.com|Artificial Intelligence]
[link|http://www.badpage.info/seaside/html|Scrutinizer]