ViewDNS.info - Free DNS related tools including Reverse IP Lookup, DNS Propagation Checker, Chinese Firewall Test...
Site Rank Data - View historical rank information of websites via time series charts.
Whats My DNS - Instantly check your domain names current IP address and DNS record information against multiple name servers located in different parts of the world.
Q-Stats - Get free marketing insights for every question on Quora.
DomainTools - Domain name research, including comprehensive Whois Lookup, Reverse Whois Lookup and Whois History.
HypeStat - HypeStat is free statistics and analytics service, where you can find information about every website.