"need" wasn't meant in that way (as in, requiring use for access). I was more meaning "the only way what I'm thinking about would work well is that it would require everyone to be using it".

re: emailing - the 'tell me who i was standing near' - yeah, some might abuse it for email. if there was some in-app functionality to allow for 'connecting', both parties might have to agree to 'connect' there to exchange contact info (and yeah, there would still be some social pressure to do so that some people couldn't resist).

Ahh... you just mentioned mutual interest - that's what I was getting at. Yeah, a 'tinder for events', based on geo location/time.