I also like this one:
JUNO: Teen fails to get abortion, ruins lives.

We have.

But the Demolition Man summary is the best.

FIREFLY: In an analogue of the post-Civil War west, a white man on the losing side bosses around a black woman.

SWEENEY TODD: Businesses flourish when freed from stringent regulation.

TITANIC: Crazy old widow disregards lifelong memories of husband, children, and grandchildren in favor of that one time she fucked a bum.

oh khan..... this is in my brain now.

YES! The Titanic one floored me.

@Dr. A: I am glad to hear that. Because my mom forwarded it to me on Facebook. So if you all hadn't seen it already I would have been .... well I guess I would have been impressed with my Mom. Which would have been a first when it comes to the internet.