Hey folks, great site! I stumbled across it tonight when I did a Google search on an N-number that I picked up off of my airband scanner. Your service is pretty darned cool.
I think that it would be nice if you had a feature that allowed me to set an alert which would fire when a flight hit its closest point to a given latitude and longitude (said latitude and longitude would tend to be…my house!) I don’t think it would be terribly difficult to implement. A simplistic approach would work like this: when you get a position update on a flight, figure out the track between its current point and its destination. Then draw a line perpindicular to the flight track, through the “checkpoint” [my house.] The intersection of these two lines would give the point of closest passage. From there, an ETA could be easily calculated, and an alert fired accordingly.
I apologize if this (or something that I could use to achieve the same result) has already been suggested.