I grew up in NYC... The cheapest movie plot generator was a subway ride.

Ride a bus, visit an emergency room, take a walk in any big city... Take any opportunity to observe humans in their natural habitat. Most people, especially today with all our insulating technological distractions, tend to try their best to shut out the world around them... Yes, it's an annoying source of gassy, rude and loudly obnoxious people, but to truly gain insight into the convoluted and perplexing reasoning of humanity at large, one must be willing to let its sights, sounds and smells permeate their being like a pair of old sweat soaked underwear. With enough exposure, one can quickly self generate stories and plots just by wading into a crowded area. Even fantasy or science fiction. I wouldn't really ever bother with software to generate a plot... The world is full of crazy ideas for stories.