Only for Ryanair, BMIBaby, Flybe and MyTravelLite so far - Easyjet would not sign up for it, wonder why, perhaps they are worried about the comparison? moneysavingexpert flightchecker
You just put in your airports and possible dates and it comes up with all the flights and fares available so you don't have to go to the websites and prat about paging backwards and forwards. I think the divine Martin is hoping to include other budget airlines in future. Brill
(small example - Liverpool-Granada between 20/4 and 20/5 (chosen at random) - on quite a few dates you can fly for 66p each way Taxes on top are probably £20 each way but still.)