Does anyone remember the money making idea from Lock, Stock and Two Smoking Barrels?
Basically involves a scam for a product that nobody will admit to owning. Once their payment for said 'product' has cleared, you then send them a letter informing 'their product is no longer in stock,' along with a cheque as refund. The catch is that the company name on the refund cheque is something dodgy and certainly not something you would want on your bank statement next month. The majority of people will then cut their losses and not cash the refund meaning you keep the money.
Obviously it is just in a film and not real, but its a funny thought!!!