Where Flight Search Engines Fail 11 years ago
Kayak explore tool is great. There have been numerous startups trying to build the same, but to make it useful one needs to have a lot of data. Kayak has arguably more data than any other metasearch engine.
Map is definitely useful and for an opportunistic traveller is a great tool. Flystein is not trying to compete with it. Where it is good though is a constrained trip, with fixed dates and requirements, or a complex trip. Map like this would not show a multi city trip.