Virus of the Mind: The New Science of the Meme

by Richard Brodie. This book is really an introduction to memetics (the study of memes) with a more contagious title (the book explains what I mean by 'contagious'). I highly recommend it, even if it is some years old at this point.

Meme:

an information pattern, held in an individual's memory, which is capable of being copied to another individual's memory.

Memetics:

the theoretical and empirical science that studies the replication, spread and evolution of memes

(definitions from Principia Cybernetica Web).