Here's some barebones Drupal 6 & 7 Services 3.0 RESTful example modules - one for D6 & one for D7.

Each version is a skeleton module implementing the framework one needs to support a single resource with each of the CRUD operations, plus relationships and targetted actions. This is similar to the "note" example, except I've further simplified it - removing any database logic, so the module is only demonstrating the necessities of getting a RESTful API operating in Services 3.0.

There is a companion module that tests the RESTful API with java script, forming the basis of a simple ajax like facility through Services 3.0.

When I first wrote these, I sent them to the Services team as a contributed example, but they never posted them, so I am posting them here.

I also host SaaS seminars and trainings at companies implementing such systems in Drupal, with an emphasis on RESTful APIs with Services 3.0. Contact me if you want such in-house training. 

I also host a free co-working space for Drupal developers in downtown Los Angeles. If you are in LA and want free Services help getting your stuff working - I'm there nearly every day: www.Droplabs.net.