Colour communication badges
Give people a way to signal how comfortable they are socialising and talking to new people.
Here’s an implementation of the system at AlterConf Berlin:
Each attendee receives three cards included with their name badge and holder. […] The colored cards can be slipped behind the name badge in the holder so they’re visible to other attendees.
A green card with a triangle means that the wearer wants people to come up and talk to them. Yellow, with a circle, means they want only people they know to approach them, and red, with a square, means that they want to be left alone. In each case, the person wearing the badge may still approach people they want to talk to, but if someone is wearing a yellow or red badge, they generally want to keep being approached to a minimum.
Note the use of shapes, so this works for colourblind attendees as well.
The system was developed by the Autistic Self Advocacy Network. I haven’t seen it at a conference myself yet, but I think it’s a nice idea.