Various groups, facebook etc., where numbers get swapped. (Supposed to be by Trackable owners who WANT virtual Discovered logs...)
Seems there are some cachers that keep an eye on newly activated Trackables, and the trackables gallery on the web site, looking for those that get the tracking number posted in a photograph.
I can see "Trackables" becoming another "Game" and no longer being part of caching, as a lot of cachers are getting fed-up with Virtual Discoveries on trackables...