In theory what is it?Cognitive Science is an interdisciplinary major. It the intersection of all fields that seek to evaluate or model human or animal “cognition.” Webster's defines cognition as, “the product of mental processes.” Some students focus on computer modeling of these processes (such as artificial intelligence). Other students might focus on the organic processes in the brain, human interaction with the world or other humans, or the psychological-type development of mental processes.
What is it used for?This completely depends on how you plan your course load. It can be anything from designing work spaces, to conducting clinical research. For this reason, before entering the major, KNOW what you plan to do with it. Even better, major in a field that is more specialized and less schizophrenic in the required courses. Cognitive Science makes for a terrific minor, if you are so inclined.
What does the major actually entail — work-wise?Typically a smattering of Psychology, Computer Programming, Human Cognition, Anthropology and Biology classes.
What kind of jobs do you get with it?I know a number of user-interface designers, some computer programmers, and quite a few graduate students bent on further specializing their skill set (in biological sciences, such as neuroscience, or in psychology or human development).
What are the fellow students like (personalitywise) in it?Usually quite creative, think-out-of-the-box types looking to try something new and exciting.