About a month ago..
Living in a metro area with roughly 1 million people, contacted a Craigslist poster about some golf clubs he had posted. We agree to meet up to look at them, he then gives the area he lives, and the area he works. I tell him I work in the same area downtown, so we could meet somewhere around there. He then gives the building he works in, and I tell him I work in the same building. We meet up in the common area, and turns out he works for the same company as me (there are 4 companies in this building), and his office is a floor above me. I am now planning on golfing with him and some other colleagues that I did not know golfed (well, I didn't even know any of them since I just came over to this office).
Pretty neat.