Has any one done this? From I can see it would seem to be useful data to figure out where you Customer base is coming from so you could tweak your campaigns. Just a question
I've been checking on google analytics but I don't have enough data to really go on but it is interesting that it goes down to city level so maybe that would be something you could somehow make use of.
It's easy to do within your own php code and if you have SQL you can store and display it from there. What I am asking is it really useful data?