Boycott movements on college campuses tend to take hold (or fade away) based on whether a critical mass of well known institutions participate. So critics of Coca-Cola have much to celebrate as 2006 begins. They say that 23 colleges worldwide have now banned Coke products from their campuses. And they have now hit a total of 10 in the United States, including bans approved in December by two large institutions -- New York University and the University of Michigan.