Short-term apartment and house rentals are getting more popular with travelers. These websites offer a convenient way to find them, and a measure of protection.

This site, which has about 8,000 listings in 58 cities worldwide, certifies hosts with good records and offers discounts from partners like Crunch gym. Guests book rooms and pay on the site, which charges an 8 percent to 12 percent fee and holds payments until check-in. Recent Listing: A one-bedroom apartment in San Francisco's North Beach neighborhood for $175 a night

Airbnb has a social vibe, with guest reviews and profile pages for hosts and travelers. It has some 30,000 listings in 157 countries. Customers book and pay for trips on the site, which charges a 5 percent to 12 percent fee and holds payments until 24 hours after check-in. Recent Listing: A private bedroom and bathroom in an apartment shared with a host in New York City's East Village for $90 a night

HomeAway, which has a free iPhone app, features 230,000 listings in 120 countries. Like Roomorama, the free service lets you search for specific amenities and policies, such as pet friendliness. Guests pay hosts directly; the site insures rentals up to $1,000 at no charge. Recent Listing: A two-bedroom condo in Chicago's Wrigleyville neighborhood for $249 a night.