Well seeing the number of Big Screen film that featured trains as the unpaid star of the show here's a few I think would make a good cases to being manufactured in O scale.
http://scratchpad.wikia.com/wi...le:Amroad_4070-1.jpg
(Silver Streak) Amroad FP7A #4070
http://www.rrpicturearchives.n...8653%5CDSC_b2759.JPG
(Unstoppable) AWVR Dash9 #767 and #777 with SD40-2 #1206, 7375 and 7346
http://cinetrains.files.wordpr...01/endoftheline3.jpg
(End of the Line) southland GP38-2 #2317
http://cinetrains.files.wordpr...riedgreentomatos.jpg
(Fried Green Tomato's) A&WP 4-6-2 #290