I've gotten caught into the flight tracking addiction as well. I've used Flight Explorer Personal
a couple times. I don't think it's as nice as AirNav but it's a reasonable $9.95/month for 10 hours (can't leave it on).
Without having to pay for anything my other favorite link is Flytecomm
. I love this one because you can look at all the airline arrivals for a specific airport for within 24 hours. Flightarrivals.com
is good too but they limit you to very small time frames.
There are two limitations that are hard to accept with flight trackers, however. First, is that they only show aircraft over the US & Canada (or at least reporting to the US/Canada). The other thing is that the data for the flights is delayed 5 minutes from real-time for security purposes (makes sense, and it wont change).
Aviation Photographers & Enthusiasts--Coordinate your life.