What purpose the YC "fridge" serves beats me too. I do, however, find the service useful. And I think "Simple Private Social Networks" says it all: it tells me

What purpose the YC "fridge" serves beats me too. I do, however, find the service useful. And I think "Simple Private Social Networks" says it all: it tells me that I can communicate with a specific group through an interface similar to that of FB, but keep it private. Sure, you can add settings that make you 100 % certain that no photos you upload will ever be seen by anyone outside a specific group of people (can you, really?). Are you certain that other members of the same group will "behave"? Encapsulating it in a "fridge" gives me some level of comfort. And you can use the full FB feature set with a limited audience. You can also communicate with a group, but not add everyone in the group as a friend on FB.