In a similar spirit, it could be cool if some coffeeshops and restaurants explicitly designated one of their communal table as a 'talk table'. Where if you sit at it, it means you are open to chatting with your neighbors.

I know that many places already have communal tables but I find that unless there's some explicit display a place is meant for a certain purpose, many people who want to chat / meet new people won't initiate because they can't be sure their neighbours are open to it. If they purposefully decide to sit at a 'talk table', then you can be sure they are.