FLIGHTS

Looking for sales on a specific route, or just want to go somewhere cheap?AirfareWatchdog.com hunts down deals computers tend to miss, like promo codes airlines include in e-mail newsletters. It also finds sales from Allegiant and Southwest, which typically aren’t listed on major airfare search engines. You can sign up for specific fare alerts or a list of all the cheap round-trip fares from your local airport.

Where can you go for $500 or less? Kayak.com/explorewill show you where you can vacation for a particular price and display the results on a map. You can narrow your search by month, region, flight length, weather or activity. Clicking on a price reveals dates the fare is available.

If you already know where you want to go, use Itasoftware.com to find the cheapest dates to fly. Click on “airfare search” in the middle of the home page, then enter your departure date and destination and select “see calendar of lowest fares.” To purchase, you must go to the airline’s Web site or online agencies like Travelocity.

To figure out whether to buy that plane ticket now or wait, go to Bing.com/travel. Its Price Predictor can determine how likely a fare is to rise or fall during the next seven days from more than 250 cities in the United States to top domestic destinations and major hubs in Europe. The site claims that its predictions are about 75 percent accurate and save customers more than $50 on average for a round trip.

After you’ve booked your tickets at an airline site, enter your flight information atYapta.com to track the price so you don’t miss out on savings if the price drops. If the difference in price exceeds the rebooking fee (typically $75 to $150), Yapta will send you, without charge, an e-mail or tweet so you can call the airline to claim the credit.

HOTELS

To get the best deal on Priceline.com, where travelers name their own price and pay before learning the hotel’s name, sites like Biddingfortravel.com andBetterbidding.com have long offered strategic advice on how to game the system. Now, a new site, Biddingtraveler.com, goes a step further. Enter the city, dates, neighborhood and star ratings for the hotel you want. Then, after reviewing the site’s recommendations, enter a “lowball” bid and “final offer.” The Bidding Traveler then calculates and helps you execute the optimal bidding strategy on Priceline.

Not willing to gamble? Hotels.com offers nearly 145,000 properties in more than 60 countries from national chain hotels and all-inclusive resorts to bed-and-breakfasts. You can find particularly good last-minute deals on Tuesdays and Thursdays. And the site has a loyalty program through which members earn a free-night voucher after they book 10 nights.

For hotel fanciers, Luxurylink.com, offers discounts on high-end hotels and villas through online auctions and deals. Just last month the site was auctioning off a five-night package at La Samanna on St. Martin in the Caribbean that included a deluxe ocean-view room with a private terrace, airport transfers, a bottle of rum upon arrival, two 45-minute massages and a one-day car rental with a minimum starting bid of $2,475. The package normally costs $6,171.

VACATION RENTALS

As hotel prices rise, vacation rentals can be the better deal. HomeAway.com offers more than 290,000 listings in 145 countries, including rentals by owners that cut out the middleman.

Airbnb.com connects travelers with locals who are offering a place to stay, whether it is a couch, a private apartment or a castle. It currently has about 100,000 listings in 19,000 cities and towns in 192 countries, and charges booking fees from 6 to 12 percent.Wimdu.com offers a similar service focused mostly on places in Europe with 35,000 listings across 100 countries. Do as much due diligence as you can when using such sites; some hosts have been known to cancel confirmed reservations at the last minute.

For luxury seekers, Jetsetter.com/homes, a members-only site, offers discounts of up to 50 percent on 5 to 10 carefully selected vacation rentals. Membership is free and by invitation only. You can also request a free membership on Jetsetter.com.

EVERYTHING ELSE

Tired of sifting through daily-deal or group-shopping sites like Groupon and LivingSocial for local bargains? YipIt.com, collects those deals from 787 services in 118 North American cities. Travelers who sign up with an e-mail can filter results by checking categories like wine tasting, museum, golf or other activities. A recent search for restaurant and spa deals in New York turned up a $60 three-course dinner for two with wine (worth $136) at Tenpenny, the Gotham Hotel’s restaurant, and a $199 Moroccan Spa treatment at the Trump SoHo, worth $339. Pay close attention to expiration dates to be sure the deals will be good for your travel plans.

Autoslash.com searches the Web for discount coupons on car rentals and applies them after you book. It then continually checks for lower rates and coupons until your trip date and automatically applies any discounts it finds.

Cayole.com lets you search cruises by price, destination, room type or cruise line, then offers price predictions to give cruisers an idea of whether they should buy now or wait for a possible price drop. For example, by clicking “get more details” for a five-night Western Mediterranean cruise in September, the site recommended that travelers booking balcony cabins buy “as soon as possible, because prices are likely to increase.” For interior ocean-view rooms or suites it suggested waiting.

If you’re willing to swap places with a stranger, list your home and find travelers willing to trade on Homeexchange.com, which facilitates about 60,000 swaps a year. Recent listings included a two-bedroom apartment on Lake Como in Italy and a six-bedroom oceanfront lodge in Cape Town with a resident game ranger. Members pay $119.40 to list their home for a year or $47.85 for three months.