Amidst the thousands of flight cancellations the past week, this tool couldn't come at a better time. Delaycast takes your flight information (airline, date and time and airport) and analyzes data from airlines and airports to give you predictions about how long your filght will be delayed. The system uses mathematical models for analysis, which are updated at least once a month but sometime more often than that.

They claim to be accurate within 15 minutes "80-90% of the time." So, I wouldn't necessarily rely on the service for planning your airport commute, but it certainly can't hurt to check it out. The top 60 airports are covered and most major airlines.