I also like http://www.qixo.com

I compare results from there with what I get from my other favorite site - http://www.itasoftware.com

I really like the way itasoftware displays the results. It makes it easy for me to drill down into those alternatives that I want to research further.

I just booked a round trip to New York JFK in October for $315 when other tools were quoting me $375 as a lowest fare. Itasoftware picked up the fact that American Airlines offered a discount if you depart during a specific one hour window.

Great topic. Thanks for bringing it up!

Mark Los Angeles