I've already had a quick glance at Plotto - it's hilarious. Written by American pulp writer William Wallace Cook in 1928, it lists over 1500 different possible plots.
My favourite so far?
"Character A, appearing suddenly among a tribe of savages, is encased in a diver's suit from which he cannot free himself unaided; nor, hailed as a god, can he ask his savage captors to free him."
Even Alfred Hitchcock is purported to have sought inspiration from (or at least bought) this book.
