This is really great, the only problem for me is that there is nobody around me! I can see it working way better for stuff like universities though.

I wonder if there could be a variant for Drop which is world wide - imagine being able to join a chat in a foreign country (hopefully you speak the language!) and chat with the locals. I imagine moderation would be a big pain but I could see it being fun and sort of in the spirit of the old web.

Right, there's an onboarding/bootstrapping problem where the first users in an area have nobody to talk to. The default radius should scale by user density, perhaps.