I remember this talk James, it is difficult sometimes. Even many of us that have been around these events from day 1, I struggle to remember everyone's names to their faces (rather embarrasingly

). I used to joke about it at Japshows with the missus. She found it really weird that we don't recognise each other, but once a username is mentioned, it's like chatting to a life long mate. Odd, but nice.
Name badges would certainly help but are a bit 'conference' like, if you know what I mean.
But I also agree that anything beyond this will just create a divide for the people that won't get anything from a proper lanyard item to T-shirts/hoodies.
Whether it's a solution for this or not, I could help sort us some clothing. I organised various embroidered polo shirts for the likes of Hyper-Rev / Prelude UK / Lude Behaviour. Now my usernamed ones for these all gather dust in my cupboard. I'd be happy too organise again, but would prefer a T-shirt or Hoodie this time. And something with a little more graphic on it so it's something nice to wear other than at a couple of car shows a year.
I can't see any other option than name badges or stickers and for whoever organises the show to be responsible to provide them at the show for everyone.