I did agency work for a while. One of our clients around 2010 was the US Holocaust museum here in DC. They had stumbled on a trove of pictures of orphaned children and needed help identifying them. We built a site to display them and integrated a handful of carefully selected social networks including Polish network Nasza Klasa. The idea was that people could share these photos and through the network effect, the museum would be able to find, tell, and archive the stories of these children. I was skeptical that anything would come of it but almost immediately, the site started getting results like "that's my father" or even "that's me". It still amazes me.
Looks like the site is miraculously still up though the Cufon is looking a little rough these days: https://rememberme.ushmm.org/
Looks like the site is miraculously still up though the Cufon is looking a little rough these days: https://rememberme.ushmm.org/