UPDATED November 2011: Check out the second edition of the webinar - RESTful API Design.
It's been 10 years since Roy Fielding first defined REST in his dissertation on Architectural Styles and the Design of Network-based Software Architectures. Since then, REST is often held as the standard for usable, well-designed, easy-to-integrate APIs.
At the Cloudstock hackathon, I presented "Teach a Dog to REST," asking the question: where are all the elegant REST APIs we'd all hoped to see? While many claim REST has arrived, many APIs in the wild exhibit arbitrary, productivity-killing deviations from true REST. In this presentation, I start with a typical poorly-designed API and iterate it into a well-behaved RESTful API. Check out the presentation (with audio!) below for rules and advice on how to do REST right, including handling complex variations, pagination and API versioning.
Slides + Audio: