I booked two round-trips for August and September back in March. Since then both my itineraries have changed multiple times. Flight numbers, airplane types, and flight times have all changed significantly. I haven't received any calls notifying me - I just check the schedules every few weeks then call them when I see a change.

Due to the slowing economy the changes seem to be much more frequent and drastic this year compared to other years. I would imagine my record for each of these flights is multiple pages now with all the changes!