As so-called baby boomers age, there has arisen a new generation to be categorized, characterized, analyzed, stereotyped, written about, targeted, and advertised and sold to. And apparently none of this can happen without first tagging it with a label. The name that seems to have stuck so far is "Generation X," taken from Douglas Coupland's 1991 novel. If nothing else, though, that label suggests an unknown quantity and emphasizes the fact that the...