I've got an idea that I'll try to make coherent enough for someone else to get the gist of...
I want to be able to post photos, messages, and other personal stuff to a site that I pay for the hosting of, which can only be read by certain people. I'd like to offer them the ability to have their own accounts and do likewise. Bonus points for making it possible for them to download and move their stuff later if they so desire.
Facebook does most of these things, if you are willing to ignore all the downsides of being a resource for advertisers to mine, and governments to spy on, and hackers to breach, instead of being their customer.
I'm thinking of coding up something based on a bedrock of capability based security, with layers of filtering restricting authority on each layer to the user.
A private version of facebook, which can be shared... it shouldn't cost much... unless someone goes wild posting video and sucking up server space. I'd guess $5/month or less.
What do you folks think?