http://www.eventful.com/

Eventful is the leading events website which enables its community of users to discover, promote, create and share events throughout the world. Eventful’s unique Demand service enables users to create grass-roots campaigns to “demand” events and performances in their city. In addition to event discovery and promotion at Eventful.com, the company’s underlying technology platform enables sharing, feeds and event data syndication to other websites, blogs, calendars and partners.