For some, college really is an investment. As online college courses have exploded, so too has fraud. A growing number of people have been registering in online education programs only to take the financial aid allotted for books and other expenses. Such crimes now make up 17 percent of the open cases with the Department of Education's Office of the Inspector General. The biggest fraud discovered so far was at the University of Phoenix, the nation's largest for-profit college, where officials found 750 rings involving 15,000 people. One woman made $128,852 while she was in prison by registering other people for classes and taking the aid they received.