Make the subway a casual and sociable place, a place where we can meet new people, make friends and network.
I believe we can do this and change subway culture because it's something that most of us want. Most of us do feel a sense of a missed opportunity during our long commutes siting in isolation with our ipods. If we can identify who we are that want to interact and specify what we're interested in, we can change our experience.
We can identify ourselves by wearing armbands. Whenever you get on the subway and want to connect with someone, put on your armband and hopefully there's someone else on the car wearing one too. Perhaps we always ride the first car. The armbands will be of different colors and patterns to indicate what we're interested in. Perhaps blue to indicate interest in discussing food/restaurants, perhaps green to get advice, perhaps purple to find someone to help you pack or move. You don't need to find someone with the same color to talk; just now you know what the other person is looking for and it's a great conversation starter.
This idea will be practical once there are enough people involved so that there's a solid chance you'll find someone else in the group whenever you ride the train. Until then we will have to start with a more systematic way of coming together in groups and popularizing this movement. I think we can start by focusing on rush-hour commuters who ride the same train every day, and uniting into a little group talking about different things every day. If will be something small and simple. Then expand into the armband idea. Eventually this will change the subway culture overall, because there will be enough people chatting on the train that it creates a communal vibe. I discuss more details on how I plan to pull this off in my plan.