I love this generator because it's not a simple fill-in-the-blanks generator—it forces you to think. The resulting story ideas are always uniquely your own.
The Story Idea Generator picks a random conflict from each of the Internet Public Library's list of 7 plots, 20 plots, and 36 plots.
This conflicts are generic enough that you must supply your own details.
Part of Holly Lisle's Professional Plot Outline Minicourse has a section on using basic conflicts to build plot. This is where the idea of this generator first occurred to me. Check out her free course. She explains how to use these random conflicts to create a plot with depth and emotion.