Here's a little gimmicky site which can lead to hours if not days of amusement. Thanks to Paul Ruven for drawing my attention to it!
And if you're lucky - it'll come up with a really useful idea! Though you may have to wait a long time for that to happen.
Try it out:
Random logline generator
The best I got up to now was this:
A restaurant owner proposes to a hysterical starship captain.
It's just crazy enough to work...