We've all heard it (and I'm hearing it now at ORD's AC): "Your flight is delayed because the aircraft on the preceding flight out of xx is delayed and not due to arrive until 6pm; your flight should leave at 6.30pm"

Is there anyway to find out where an airplane is coming from before you board it? For example, I'm on flight 1844 from ORD to EWR, but that airplane is coming into ORD from somewhere else. I guess I can take a wild guess using a combo of aircraft type, AA timetable into ORD, and delay information. Does anyone know of anything better.

For example if there's something that tells you the tail number of your flight, you can then track the tail number in flight tracker or one of those software packages.

Thanks in advance, sorry for the long post.