Also known as photographic memory. Eidetic memory is the ability to remember things with absolute clarity--not just stupid things, like the symptoms of amylotrophic lateral sclerosis, the lyrics to Underworld's immensely popular song Mmm, Skyscraper, I Love You or the coefficient of drag of an airborn Holstein cow. We're talking about useful things here, such as the name of your first-grade teacher's assistant, or the chemical formula for Bryll-Creem.