Turn Off Your Fog of War
Wow, apparently the FareCast beta has added even more cities, making it a viable service to use for the majority of readers. In a nutshell, it lets you see how the airline industry will try to game you by using historical data to offer expensive fares during popular times. By avoiding the price spikes, you can get a lower fare, especially if you are flexible with your travel dates. Check the writeup here.