If you work in an FBO or are a aircraft enthusiest, you will find this useful. You can track aircraft for your local airport or look up a tail number. It is great for tracking that pesky late airline flight you were suppose to be on, .
This is not of the fault of Flightaware, but if a pilot has his tail number blocked you will not be able to track it.
This is the best flight tracking service i have seen , free or paid for.