I subscribe to a great travel blog, Upgrade: Travel Better, which recently ranked some of the airfare search websites out there: Kayak, Sidestep, Mobissimo, TripAdvisor Flights, Momondo, Skyscanner, WeGo (formerly Bezurk), Trax, Farecast, Fly.com, and Dohop. The overall winner was TripAdvisor, though Kayak came in a close second. It seems that the main reason TripAdvisor edged out Kayak is because it gives you an estimate of the total cost of your flight, including baggage check charges and other fees. Both sites are good bets for domestic flights, while Kayak and Trax are best for international flights originating in the U.S. The blog also identified the best sites for first-class and business class tickets, as well as inter-Europe travel, and offers individual reviews of all the included sites. Check it out here.