Chain Letters Are Not Legal Postal Service judicial decision that debunks the claim that sending a "report" in exchange for cash makes a chain letter legal. http://www.usps.com/judicial/1978deci/6-72.htm
Skeptic's Dictionary: Pyramid Schemes, Chain Letters and Ponzi Schemes Defines these fraudulent systems of making money which require an endless stream of recruits for success. http://skepdic.com/pyramid.html