Has the FAA ever granted anybody a license honoris causa?
It's an interesting question, and according to AOPA they did award one to the guy who designed the current FAA license card:


  The FAA awarded Dahlvang his own (honorary) certificate, nicely framed
  with a gold seal.


But it doesn't say what's printed on that certificate and I assume it isn't actually valid for flight. If you give someone a real pilot's license you give them the authority to operate an aircraft and I can't imagine the FAA handing out licenses to unqualified people.

Orville Wright did get an honorary certificate, as did other 'old-timers', but that pre-dates the FAA and again it isn't clear if they were 'real' certificates or not:


Orville Wright
Evan J. Parker


I don't know if that really answers the question, but anyway in practical terms I think it's probably a lot easier for the FAA to come up with a suitably impressive but legally worthless certificate rather than give someone a real one and deal with the legal issues involved in breaking their own rules and possibly federal law.