SimilarWeb - SimilarWeb.com is a website analysis tool that gives you analytics information for any website.

Google Groups - Google Groups allows you to create and participate in online forums and email-based groups with a rich experience for community conversations.

Website Informer - Website.informer: complete data lookup & free aggregated report on any domain including whois, visitors, IP & DNS details, competitors, owners, etc

DownToMeet - DownToMeet is a platform to organize, find, and attend group events.

Site Rank Data - View historical rank information of websites via time series charts.

Mighty Networks - Mighty Networks enables entrepreneurs, organizations, and companies to create and grow a community-powered brand.