At my second job, there was quite a commotion in the office one week, when my boss started receiving a steady stream of random people's CVs. It turned us a moment to figure out what's going on - turns out, there was an ad for seasonal fruit-picking work, which listed [lastname].[firstname]@gmail as the contact address; my boss had a [firstname][lastname]@gmail address, and a subset of wannabe fruit pickers were reversing address components for some reason (with the dot conveniently being an ignored character in GMail).
Don't remind me. I spent forever trying to figure out why I was still being charged for an Xbox account I'd already canceled. Turns out Microsoft had one account with the dot and one without.
