Some general Delphi resources:

• Rad Studio Dephi Technical Resources : some programmer's links - videos, in depth articles with sources, manuals, demonstration programs, trainings
  
• The creation of Turbo Pascal : the insider story about the creation of Turbo Pascal
  
• Delphi INDUC A virus anatomy : presentation of the INDUC A virus which spreads by compiling Delphi programs. The technique, the source code, the evaluation
  
• FireMonkey Styles : changing styles for all or for some components, the Style Designer, content of a .STYLE file, setting then StyleLookup property, predefined styles.