Kayak.com – Hands down the best flight/hotel/car search aggregator! Search multiple airlines, hotels, and car rental companies all at once, with a great user interface that allows you to immediately filter results according to your every whim.
Hotels.com – Gets you the best deals on Hotels.com by working directly with hotels to reserve unbooked rooms. If you know where you want to go, Hotels.com can make your stay affordable!
Priceline.com – Priceline gives you two excellent ways to book travel! Their site gives you the option to either purchase at a set fare, or submit your lowest bid for airlines and hotels to accept or reject.
Travelers who want to choose specific carriers or hotel sites can book the set discount fare, while the more adventurous can offer their price of choice for great travel.
Travelzoo.com – Every week Travelzoo publishes an e-newsletter containing the Top 20 hottest deals in travel. Get unbelievable deals and discounts on flights, hotels, even attractions like theater tickets and theme park admission!
With Travelzoo, you can view by destination, trip theme, or deal type. Soon you’ll find yourself lounging on the beach at a 4-star resort for a 2-star price!
11thHourVacations.com – This site specializes in last-minute travel. As the clock ticks down to departure, the lowest prices can be found at 11thHourVacations.com on everything from planes to trains to automobiles!
Their focus is vacation packages, so if you’re looking to book only one component of a trip, you’ll find better deals on other sites.
TripMania.com – One of the lesser known vacation websites, TripMania is not to be overlooked for awesome vacation packages!
Their search features not only let you choose specific travel parameters or browse by trip destination/style — they offer an RSS feed to notify you immediately of the newest discounts!
LastMinute.com – If you’re looking to escape the daily grind for a long weekend getaway, you can save up to 70% with LastMinute.com!
This site regularly has amazing travel package discounts to the hottest destinations. Booking one to two weeks before your departure lets you score the best trips for the least cash.
IntrepidTravel.com – Specializes in exotic locations and cultural immersion, with truly once-in-a-lifetime experiences. Looking for a vacation to remember? Broaden your horizons for 20% off all trips departing soon — a consistent discount on this site!
Expedia.com – With frequent discounts and promotions on a huge array of flights, hotels, rental cars, cruises, and packages, Expedia is a one-stop travel shopping source for every budget. This site is so popular, it even has its own frequent user rewards program!
Travelocity.com – Similar to Expedia, the Travelocity website searches major airlines, hotel chains, and cruise lines for their best rates. Any fare booked through Travelocity is guaranteed, so rest assured you’ll find the best prices here.