Thrillist has a list of the 100 greatest film props, and the stories behind them, edited by Matt Patches and illustrated by Jason Hoffman. No costumes or vehicles allowed, just real, physical props—and pretty hard to argue with that number one. From the introduction:

They are sketched out, improvised, or placed in scenes by the fate of logic, existing to serve the performances or action around them. But while iconic movie props make us laugh, gasp, scream, and/or sit in absolute silence, they rarely start iconic; as a property master will tell you, the best on-screen objects go unnoticed, silently winning you over with truth.