FlightCaster is a web application that offers information on flight delays. According to FlightCaster,
FlightCaster predicts flight delays. We use an advanced algorithm that scours data on every domestic flight for the past 10-years and matches it to real-time conditions.
That means you can use their site to guess if your flight (or that of your loved ones) is going to be on time. Here's a colorful sample. You can also check on airport weather and ground delays imposed by the FAA.