This ancient story led Freud to coin the term "narcissicim" to refer to someone who is self-obsessed; you can read more about the psychological dimensions of narcissicism at Wikipedia.
Narcissus also gave his name to the flower "narcissus," also known as "daffodil." Ovid, in his Metamorphoses, tells us that after he died, Narcissus was turned into a daffodil. You can read Ovid's version of the story at Tony Kline's website: Ovid's Metamorphoses in English.
Here is a medieval depiction from the British Library's Harley 1766 ms.