Playing as a Roman you can park a ship just outside a greek port, say Sparta, keep a diplomat next to the same city. Within a turn you can blockade the port (going to war with them), and then immediately have your diplomat offer a cease fire in exchange for a tidy sum. Within a single turn you can do this multiple times since it takes no move points once you are in location. I extorted about 10k each time until the Greeks were drained. Is this a bug, or am I taking advantage of a scared faction? I have not seen if this works with other factions.
Sorry if this has already been posted, but I hadn't noticed it.