According to UK's The Sun, technology that Facebook recently patented could be used to suggest friends based on who you've been standing near.

The technology would use, in-part, Bluetooth signals (and signal strength) to determine who you are standing next to.  Additionally, it might search other social media platforms (like Instagram) or your contact list to determine who you may want to connect with.

Yes, it is kind of creepy, but I see some good uses for it.  It allows you to easily connect with someone who you may have met at a charity event, business meeting, or bar / club.  Someone that you may have had a conversation with, but whose contact information you never thought to get.

There's no guarantee, at this point, that Facebook will ever use this technology to suggest friends.