The Last.fm JavaScript Library by Felix Bruns allows developers to access the Last.fm API's methods from their JavaScript applications. Usage examples are provided in the documentation.
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."
There was a bit of stir this week when the small music web site YottaMusic had to shut down because they were no longer allowed to use undocumented Rhapsody APIs.
