Foursquare - Foursquare is all about helping you find new ways to explore your city.
Mighty Networks - Mighty Networks enables entrepreneurs, organizations, and companies to create and grow a community-powered brand.
Flamp - Reviews of companies in your city.
Bigtent - BigTent is a web-based organization and communication portal for groups.
Yelp - The free Yelp mobile app is the fastest and easiest way to search for businesses near you. Download it now to get started.
Nabble - Nabble is a forum software that are embeddable and fully customizable with scripting language.