I have just completed the application process for an ESTA (an American electronic travel 'visa').
Going through the process I was surprised to be asked for details of my social media accounts. It is an 'optional' part of the process, but I wonder how many people complete it (in all its gory detail, and there is a lot of detail). Indeed, I did not realise just how many social media sites there are beyond the big-5 (Facebook, Twitter, Instagram, Google+, Snapchat). As I write that, I realise that I have missed out the big Chinese sites and—no doubt—many more. So perhaps their list is not so big.
I was also asked for any other nationalities and passports I hold (including expired ones). That part was not optional. Alas, I do not really keep the details of old/expired passports.
But it really makes me think about how folk are trying to build up network diagrams of our/peoples' relationships.