DNS LOC
Works to geo-enable the domain name system, presenting maps of known sites for the USA, Europe, and the rest of the world.
DNSstuff.com
Provides DNS tools hosting tests, WHOIS services, ping, and other network domain name tools.
Fusion
Domain Name System resolver that provides a library of routines a client application can call to perform the domain name to IP address translation function. Also features utility routines that help integrate DNS server responses with a client application.
Net DNS
DNS resolver implemented in Perl. It allows the programmer to perform nearly any type of DNS query from a Perl script.