Nearly 23 percent of all mortgages taken out in 2005 were interest-only ARMs, and more than 8 percent were payment-option ARMs, according to First American LoanPerformance.

NPR: Mass. Homeowners Rally Against Foreclosures

Write-offs for option ARMs at Washington Mutual, a stumbling thrift, have zoomed from 0.49% in the last quarter of 2007 to 3.91% in the second quarter.

ECONOMIST: American housing 2: Ticking time bomb | The

With payment-option ARMs, borrowers get to choose how much they pay each month: enough to cover the interest plus the principal, the interest only... or less than the interest.

NPR: Mass. Homeowners Rally Against Foreclosures

This is the simplest of examples, but bear in mind that more exotic mortgage contracts like option adjustable rate mortgages (ARMs) and such can leave the household in a similar situation, facing not only impaired equity but also higher payments.

FORBES: Magazine Article

Others may exercise their option to "go nuclear, " contributing to regional arms build-ups and proliferation.

CENTERFORSECURITYPOLICY: Obama's shrinking deterrent

This "strategic" approach to arms control, which always insisted on retaining the option of modernization and never took risks with verifiability, was nearly overwhelmed by assaults from two opposite directions.

CENTERFORSECURITYPOLICY: Center for Security Policy | Kissinger Rebuts Clinton & Co.��s Claim that C.T.B.T. Was Defeated by Partisan Politics, Isolationists