Some loans that seemed novel just a year or two ago have become almost mainstream. One example: interest-only mortgages, which allow borrowers to pay interest and no principal in the early years of the loan. A drawback of an interest-only loan is that you don't build any equity during the interest-only period, which can be as long as 15 years. If home prices fall, borrowers can wind up owing more than the home is worth.

"Piggyback loans" have been popular, too. They combine a standard first mortgage with a home-equity loan or line of credit. Piggyback loans were first used as a way to get around private mortgage insurance, which is required when borrowers take out a mortgage that exceeds 80 percent of the purchase price. They also have found favor with borrowers trying to avoid paying the higher rates charged for jumbo loans, currently any mortgage above $333,700. Someone borrowing $400,000, for example, might take out a mortgage for $325,000 and a $75,000 home-equity line of credit.

Lenders also are retooling products that fell out of favor years ago. One example: so-called negative amortization payment options, which let cash-strapped borrowers cut their payments to the bone. You make a minimum payment based on interest rates at the start of the year. The downside: If rates rise, borrowers can wind up owing more than when they started.

Negative amortization loans got a bad name in the 1980s when interest rates soared, and some borrowers walked away from their loans. But they have resurfaced in the past year in short-term adjustable-rate mortgages that let borrowers choose one of four payment options each month. One is a minimum payment that can lead to negative amortization.

Lenders say they have tightened their lending standards and now do a better job of explaining the loan's risks, and the loans have resurfaced lately, with consumers lured by initial interest rates as low as 1.25 percent.

As lenders look for new niches, even borrowers who worry about missing a payment have a loan that's tailored to their needs. Some lenders let you skip up to two payments a year, or 10 payments over the life of the loan, without ruining their credit. But such loans aren't cheap.