Turning from ancient epigraphy to contemporary epigraphy: Today, Google Street View went live in many Canadian cities, including Montreal. As I’m currently putting together a book prospectus for Stop: Toutes Directions, this is of great interest to me. Google’s images aren’t high enough quality to evaluate damage, wear, and vandalism, much less actually photograph and read the vandalism. On the other hand, it does allow me to easily identify new (currently un-surveyed) areas where there is a lot of linguistic variability. It took me about two minutes, for instance, to find this intersection at the corner of Churchill and Cornwall in Ste-Anne-de-Bellevue, a bilingual community at the western tip of the island of Montreal, where there are two ARRETs, one STOP, and one ARRET/STOP at a four-way intersection. We only have a handful of intersections with all three sign types in our database currently. Or alternately, one of our pet theories is that airports and border crossings tend to have greater numbers of bilingual stop signs, and this could be checked out rapidly without needing a road trip. Just as Google Earth allows archaeologists to find new sites online, but requires a lot of ground-truthing, Google Street View is a handy tool but doesn’t let you skip the hard part. For any of my co-authors who may be reading, though, rest easy: I’m not about to freak out and ask you to start collecting new data online, although I did think about sending you a prank email to that effect, before I thought better of it.
Glossographia 
I’ve only just started looking at your blog (so excuse me if this is a point with which you are already familiar) but having just come back from a holiday in France was amused by the idea of ‘bilingual’ Stop/Arret signs. In metropolitan France, signs say ‘Stop’.