When I was at UK, we sorority members helped the freshmen move in every year. We wore jerseys with letters & as such represented our own chapters. I like the idea of not being able to tell - this does further the Panhellenic aspect.
I'm thinking of things like helping the new colony on campus have a smooth recruitment (for instance, at UK Alpha Phi just opened 2 years ago, and Phi Mu is colonizing this year). I'm talking about any effort to get beyond "your own chapter" and include others in the general recruitment theme.