I don't hear people mention Drupal much here at HN. I assumed it was the learning curve; but anyway.. I point your interest over at https://drupal.org/node/783460 where the Services 3.0 module's REST API development framework is demonstrated with an example of creating a simple RESTful CRUD service. For ambitious WebApps & WebAPIs, Drupal provides great scaffolding for development. And it looks like the Drupal8 branch, a few years away, is 'headless' as in being configurable to only be an API endpoint with no "web site" necessary.
Using Drupal to create a RESTful API is like using a tank to hammer in a nail. It takes about 50 lines of code to write a simple RESTful API in pure PHP.
