Request for "Minutes Before Arrival" Alert

As a daily user of FlightAware’s live tracking capabilities, which I find to be the best among all related websites out there, the feature I miss the most is to be able to set alerts when the flight is in range. It would be cool if, besides take-off, landing, etc, a couple of alerts could be triggered when the flight is xx, yy and zz minutes away. Hope you can add this feature sometime.