Additional Information
Apple Developer Documentation
The Apple Developer Connection website contains a wealth of information about Services and how to implement them. The following links are provided to give you more information about the inner workings of Services.
Introduction to System Services
Introduction to Copying and Pasting
The NSPasteboard Class
Ruby Resources
If you would like to learn more about the Ruby programming language, the following resources are a good place to start:
Ruby Home Page
Ruby Central
RubyGarden
Programming Ruby Book (Recommended)