On Adioso (adioso.com), not only will you be able to use the traditional queries such as destination and dates, but you will also be able to type in the city you are leaving from, the city you want to get to and the dates of your arrival and departure into a search box to see suggestions for different flights. Although the prices on Adioso are pretty good, it must be said that there are cheaper websites to book your flights from. However, Adioso's co-founder, Tom Howard, announced recently that there would be a price-drop coming soon on the website. hipmunk.com The interface on the website is extremely clear, fast and easy to use, which makes looking for flights a very comfortable and satisfying experience. Also, this website will order the flights from best to worst rather than from cheapest to most expensive, making you realize that the cheapest option isn't always the best one. However, if what you really want to find is very cheap flights, you will find plenty here. Google Flights Google is one of the best and most popular search engines, and it also now lets you look at and book flights to every imaginable destination. The interface is extremely simple and the prices are really good, especially now that a very low-cost company, Ryanair, has partnered with Google Flights. momondo.com Looking for a website where you can book just about any flight to any destination in the world at the best possible price? Then Momondo is the website for you as you will find some of the best destinations for the lowest price online. Kayak - kayak.com But if there is one website with the lowest prices out there that is definitely www.kayak.com. This website has been offering the cheapest flights since 2004.