My son had a photographic memory from an early age. At two years old he had memorized the names, shapes and positions of the 50 states, including the names and locations of their capitals. In the days before cell phones, PDA's and smart-everythings, he was our walking Rolodex. He knew the names, phone numbers and addresses of about 50 of our friends and relatives at the age of 3! He was also reading at that age, but he didn't learn the way most of us learn to read (by phonetics and repetition). He would point to a word that he didn't know ("ladder," maybe) and, upon hearing it once and looking at it on the page, knew it--its spelling, its pronunciation and its meaning--forever. No stumbling the next time he came across it. In later years he could draw for an image of what had been on the blackboard at school that day.
Strangely, this extraordinary talent faded away on its own so that, by the 5th grade, he struggled to memorize words for the school spelling bee and was sent out several rounds before the end. His memory is now quite ordinary.