The promise of easy money comes in an official-looking envelope marked, "Important Financial Information Enclosed." Need $2.5 million at 1 percent to 2 percent to buy or refinance a home? No problem. Borrowers put no money down and pay just interest. A good credit rating is not a requirement. Bankruptcy judgments, debt charge-offs or tax liens don't matter, and "all difficult credit scenarios are okay," the lender says. The home-financing offers come from an army of mortgage brokers estimated at 250,000 nationwide, many operating outside the reach of banking regulators. They have become the principal source of home financing in...