DD2 was breech at my 34 week appointment (noted via ultrasound). During that same appointment, there was a fire drill and I had to walk down the stairs (we were on the 6th floor) and then walk back up those stairs to finish my appointment. Once we finished the appointment, we noticed that the baby was vertex. Apparently all that stair walking helped.
She was born 2 weeks later at 7 lbs 2 oz, so she was a pretty decent size when she flipped.