Most deal-hunting travellers have Google's ITA Matrix in their arsenal. The only problem is, you can't book flights directly through Matrix. You just get the info, then search and book the flights yourself. Book With Matrix makes it dead simple to do this, though. Just copy and paste. To use the service, look up your itinerary on ITA Matrix as normal, then select all and copy. From there, head to BookWithMatrix and simply paste the entire selection into their search tool. The site will find the exact flights Matrix references with links to book directly on Priceline, Orbitz or CheapOair.
It saves you the step of having to look the flights up yourself, and it's really easy to use. Check it out for yourself at the link below.