Here are some Object Oriented Programming and Component tutorials and projects:

• Delphi Virtual Constructor : VIRTUAL CONSTRUCTORS together with CLASS references and dynamic Packages allow the separation between a main project and modules compiled and linked in later. The starting point for Application Frameworks and Plugins
  
• Delphi Generics Tutorial : using Generics (parameterized types) in Delphi : the type parameter and the type argument, application of generics, constraints on INTERFACEs or CONSTRUCTORs
  
• Why Generics Constraints : are generics constraints absolutely necessary to compile generic source code into binary code ? In short flexibility vs security.