When I pick someone up from the airport, I hate getting there and finding out that the flight is delayed an hour, or even worse, the flight got there early. I found a nifty little website that allows you to track a flight (it even gives you the status of the light via google maps).
Besides tracking flights, you can also track delays at every airport in the United States (and some throughout the world). They give you two different type of airport statuses; one from the FAA and another based on ground issues at the airport. You can even get an RSS feed of airport delays.
You can also reach the website on your smart phone at mobile.flightstats.com.
Through an agreement with Google, you can even track your flight by putting in the airline and flight number into a google search bar.
It is a nifty website that can save you a lot of time. And, you will always be at the airport right when you need to!