Seattle-based Farecast has opened up its airfare predictor service to routes for the 55 busiest airports in the United States. Previously, the company had limited its service to flights originating from Boston and Seattle.

Farecast's site is not responding right now. When we tried to use the service, this popped up:

"Sorry, it's a bit crowded. Our servers are experiencing a high volume of search activity. Please try your search again in a few moments to view the latest fares for your trip, or search yesterday's fare results while you wait."