- own a pseudo-TLD like .com.me and are really just creating subdomains
- have a large account / custom pricing deals with a domain registrar such that despite a high total cost, the marginal per-domain cost is approximately $0
- only internally-routable domains e.g. /etc/hosts or company-internal DNS server
- only alternative DNS roots like Namecoin or tor's .onion domains
- http://www.freenom.com/
- work-for/own a domain registrar
- own a pseudo-TLD like .com.me and are really just creating subdomains
- have a large account / custom pricing deals with a domain registrar such that despite a high total cost, the marginal per-domain cost is approximately $0
- only internally-routable domains e.g. /etc/hosts or company-internal DNS server
- only alternative DNS roots like Namecoin or tor's .onion domains