Once I tracked a flight back 5 cities but this required knowing where one of the earlier flight came from (with a different flight number).

Generally when I call the AA desk and tell the agent that my flight is going to be late they don't believe it until I share with them the incoming flight number. I believe they told me at one time they used to be able to do this type of search but cannot anymore.

One big word of caution, this can backfire. I was in MCI and my flight was delayed by an hour because of the inbound flight (simple to figure out at the non-hub airports), so I stopped for a leisurely lunch. Just as they served my food I got a text message from American saying my flight was now leaving in 20 min. So grabbed the food to go and jumped in the car, in the process of trying to eat and drive 80 mph to the airport dumped half the spagettii sauce in the passenger seat, dropped the car at hertz (can't ding the cars but you can drop food on the cloth seats) left the keys and didn't wait for a receipt, got pushy with TSA as they decided that's when they had to do some extra checking, got to the gate with 5 min to spare.

Of course they still didn't board for 20 min. But the moral of the story is that AA has a maintenance center at MCI and rolled out a 'new' plane to replace the delayed inbound flight.