Eventful API

From their site: The Eventful API allows users to search the site database. Eventful is the leading events website which enables its community of users to discover, promote, create and share events in local markets throughout the world. The Eventful 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 underlying technology platform enables sharing, feeds and event data syndication to other websites, blogs, calendars and partners. The same platform upon which Eventful.com is built is available to developers to build upon.

The RESTful API provides many ways to search through our events, venues, performers, demands, calendar, groups, and users. Responses are formatted in either XML, JSON or YAML.