The Take.io API from Brazil has a REST protocol with data formats in XML and JSON. According to Take.net, "The take.io RESTful API currently defines five services: SSO, Core, Billing, Messages and Reports." The company states further that, "Take.io is Take.net DNA translated into a set of APIs designed to allow companies to use SMS, MMS, voice, pricing, location, CRM, etc., all of which are integrated with their existing systems."
For staying up to date with band tour dates, live venue information and more, Pollstar has it covered. It's a trade publication that covers music industry information on a worldwide scale. What's pretty cool is that Pollstar provides an API that allows third party developers access to the full event database, enabling them to include Pollstar data on other websites and applications.