Mmm, I prefer Dohop above Floogie. Floogie has the same disadvantages as most of the flight search engines: they only search flights from the exact indicated city pair, whereas Dohop does include the low-cost alternative airports.
For example, looking to go from Dusseldorf to Barcelona, Floogie only searches for DUS
, whereas Dohop includes DUS
for Dusseldorf, and BCN
for Barcelona. IMO this is quite useful for this kind of search engines.