More serendipity: Tim knows someone doing work for nTags, which look interesting:

nTags are designed to work in harmony with normal social interactions. They provide a key piece of information at just the right time or suggest an introduction to just the right person. And they do all this without requiring any action from the people wearing them – no reaching into pockets, pushing buttons, or writing on screens. Instead of distracting people from connecting with each other, nTags encourage connections.

For example, when I walk up to you, our nTags automatically beam data to each other. Then they display messages based on that information. Perhaps I am trying to meet someone who is hiring marketing managers. Your tag may tell me that, although you are not hiring, you met someone who is ten minutes ago. Or the tags may tell us that we both love yoga and have an interest in genomics – just the information we need to start a meaningful conversation. The possibilities are limitless.

nTags also have radio transmitters and receivers, enabling them to communicate with a base station. Event organizers can send messages and updates and can even conduct audience-response polls. Participants can send messages and can upload data about the people they have met.

[reference: from the nTags site]