Site Rank Data - View historical rank information of websites via time series charts.
Website Informer - Website.informer: complete data lookup & free aggregated report on any domain including whois, visitors, IP & DNS details, competitors, owners, etc
VALBOT.COM - VALBOT.COM provides domain name valuations.
SimilarWeb - SimilarWeb.com is a website analysis tool that gives you analytics information for any website.
Q-Stats - Get free marketing insights for every question on Quora.
Quantcast - Quantcast Corporation is a digital marketing company that provides free audience demographics measurement and delivers real-time advertising.