Kayak buzz is one that I've already been using. Unfortunately they don't have a lot of great fares from international locations, because they only show fares that other people have searched on.

So if they don't have a fair number of people based in a city doing searches, they don't have a lot of good results. Kayak isn't very popular outside of the US and has limited functionality for intl cities (it searches the American site prices rather than the Asia site prices of an airline which often has much higher fares) so you don't get great results in most cases unfortunately.