If you're traveling in the United States this weekend, remember that the giant snowstorm that hit eastern states has severely disrupted air travel. Definitely make sure to get in touch with your airline before heading out to the airport, and you may also want to download FAAwait, a handy mobile app available for download from the App Store.
FAAwait provides realtime data on air traffic delays at all U.S. airports. The app depends on a data feed maintained by the Federal Aviation Administration (FAA) - one that tracks everything from departure and arrival delays to ground stops and ground delays. It doesn't do it by flight, but it should give you a sense if you're going to be walking into a mess when you get to the airport.