Richard Dawkins coined the term meme in his 1976 book "The Selfish Gene", to a describe a cultural analog to the gene. According to his theory, just as there is ones genetic information is passed on from generation to generation through DNA, there is a unit of cultural transmission called a meme, which accounts for how ideas and jokes and urban legends get passed on. I've always liked the idea and was originally going to do my dissertation on the implication meme theory had on the information world, but my supervisors face turned white and he started frothing at the mouth when mentioned the idea, so I did something safer instead.