I'm thinking of this question:
It's a textbook "Belongs on Superuser" question, but if it were migrated, it'd be a duplicate. The question that Ignacio quoted in his answer is virtually identical (and has a good answer from Ignacio.)
I voted to migrate, but then a second later I wished I could change my vote to simply close. I know it's still off-topic here, but I think the "damage" by having an off-topic question here is less overall than moving it, then having it closed as a duplicate there.