GigaOM writes that Farecast, a travel search engine that uses statistical modeling to predict if the prices of tickets will increase or decrease over time, has added cities, to include 55 U.S. cities. Wired News takes the "matter of fact" approach to their coverage of Farecast, describing "turns out 13D paid only $300 for her flight, while 14E shelled out nearly $1,000 for his."
Whenever I travel, I always try to track flight costs either based on mental note or by writing it down. I may track fares for a two to four week period and base my buy or wait decision based on that data. But often, I forget to check on certain days or I start my ticket purchase cycle too late in the game. Farecast keeps track for you.
I just bought tickets to go to St. Louis, and now I see that my purchase decision was in fact correct. Farecast says buy. The AJAX like interface plots the prices over time, you can increase the charts to see a larger version of the fare increases and decreases over time. Finally, if you are flexible, you can plot multiple destinations from one origin, to see which flight is the best for your buck.
I know I will use this tool. I just hope they add some more cities.