Dohop is one of those websites that gives you awesome information and you wonder why you've never heard of it. It basically lets you build your own search engine by searching round-trip or one-way flights between any two locations and then giving you all your options, starting with the least expensive. It searches over 600 airlines and shows you the best fares possible, even if it means flying to or out of a different airport in the area. It's the only intuitive search engine that I know of that gives you these options without you having to tell it you are willing to fly in or out of surrounding airports. If you want to book, Dohop directs you to the right website to reserve your flight(s).
You also have the option of using Dohop Away, which is a great function for finding new places to visit. Enter your starting airport and when you want to travel and you will get a list of all the flight deals available for that timeframe. Pretty easy to just click and choose a vacation and then decide what to pack!
Dohop also has a great search function to find you low-cost hotels and car rentals worldwide. I also recommend you signing up for their newsletter. It is quite witty and has some great information, including guest posts from other travel bloggers (like me!).