I propose a collection of thematically related interactive installations, called the "Eye Contact Systems", which explore the potential of gaze as a primary new mode of human-machine communication. The projects address the questions: What if artworks could know how we were looking at them? And, given this knowledge, how might they look back at us? The proposed artworks investigate the aesthetics of interactive systems endowed with new perceptive capacities -- the ability to know where we are looking -- and new expressive means, through mechanical eyes that can return and address our gaze.