We first just did badges, but that's really easy to game and some people troll others with rude badges or wait until people add badges to their profile and then turn the images into porn. Very funny.

Then we thought a handshake method would be good, so that someone can give someone else part of their WoT, if they know them IRL.

And there are also ways to gamify the handshake at meetups, by using techniques that requiring seeing the same thing or connecting over Bluetooth, or whatnot.