OK, so, just for fun, I spend 59p on the tricorder app for iPhone and put it on my iPad...
After all, iPads are just star trek gadgets made real FFS.
It is, of course, a simulation of a fictitious device, so just fun, but it has a mode to track other tricoder users?!?
Good, but what is a concern is that it shows up three other tricoder uses within 3km of my house FFS.
And I thought I was the only geek in the village :-)