I didn't know about "whois", so I searched and found that there are 5 main zones :

North America = ARIN : http://www.arin.net/whois/index.html
Europe/Middle-East/North Africa = RIPE : http://www.ripe.net/perl/whois
Asia-Pacific = APNIC : http://www.apnic.org/search/index.html
Latin America = LACNIC : whois.lacnic.net
Africa = AfriNIC (Whois run by ARIN)

I guess it's not possible to find out somebody's postal address through this ?