For Airbnb -- along with Craigslist and rival rental sites like HomeAway -- the threat of foreclosures is bringing a surge of listings. ... With US unemployment near a 26-year high and foreclosures in their fifth year of increases, there's no shortage of homeowners seeking relief. Using Airbnb presents risks, though. Renting rooms forces homeowners to share space with strangers, and amid a backlash from the lodging industry, there could be legal challenges.