Farecast is now available to for 75 cities! The website that predicts the best air fare prices on a given day based on historical data was previously only available for Boston and Seattle.
Farecast is basically an airline fare search engine. I am not sure just how good it is at that, and suggest that you compare it to your current favorites before you buy anything. What Farecast offers that is unique is a tool that tries to predict when the lowest prices can be found between any two cities. Unfortunately it appears that this tool only works for flights between the 75 cities that are in its database. I could not get a price on a flight between Phoenix and Fairbanks, for example, because Fairbanks is not in its database.
However, this is a big move up from the original two cities that previously made the site a curiosity, but not very useful. The intend to continue to grow the database, and I will look forward to the day when they also add international cities!