You're probably familiar with mind mapping. If you're stuck on a plot, a variation I call Consequences Mapping might be helpful especially during the early stages of developing your story.
You start with one thing you know you want to have happen in your story. For an example, let's say you want to write a story about how losing one's job can lead someone to extreme actions (this could be a short story or part of a novel or screenplay). You know that the character will lose his job, so that goes on the left.
Draw three lines out from that, one upward, one straight out, one downward, and attach one possible response to each of them. These might be: in retaliation he trashes his office/ he takes valuable information with him on a memory stick/ he decides to sue the company.
From each of those, draw a line and jot down at least two possible consequences.
Trashes his office: he's arrested/ he's blacklisted within his industry
Takes valuable information: blackmails to get his job back/ sells the information to competitor
Sues the company: is offered a payoff to settle/ is counter-sued
You can keep branching out with the further consequences of each development you write down (start with a big piece of paper and write smaller as you go along). It's an excellent way of generating loads of plot points quickly. Of course some won't fit the character you have in mind, and that's fine; ultimately you'll choose only the actions and reactions that make sense.