Flickr, the photo sharing site,has been the best tool I have found for finding relatives, or them finding me, with photos. I will try to mention some of theups and downs. On the postive, you can set your photos to who can see them, the public or friends and family. I had one photo of a tombstone set to public and a lady in Colorado was doing an internet search on her g grandmothers name and my photo came up. She did not know where she was buried . From there, she sent me photos of a large wall portrait that they had in Colorado ( the person in thephoto lived in Ky) Had it not been for Flickr, this photo of by gg aunt would never have been known. From there, this led to an exchange of more photos. This story has actually been repeated several times from different branches of my tree.
The down side is the public aspect of it. When putting your info in, it will come up in search engines. Once, some fellow stole my photos and tried to pass them off as his own on another site.He even said that he took my photos! But overall, I would have to say that Flickr has been worth it to gain photos I would never have had access to any other way. You can post up to 200 photos for free.