There are enough social networks for the blind,
$1 and
$1 being the too largest, that I don't think I'd use yet another. Also, social networks for the blind just tend to be virtual ghettos. That's why I'm a fan of a community like this one; we're using exactly the same site everyone else is, and /r/blind doesn't have to be the only community we interact with. We also get a lot of sighted people like yourselves coming through, who might not bother signing up for a "blindy" website. So it's far less isolating. My advice is for you to focus on new and innovative ways to make existing social networks accessible, so blind people can have an easier time interacting with our friends and family online, and making new friends on the wider Internet. Currently, I'd say Twitter is pretty much a solved problem, as there are enough clients for blind people that I don't know anyone who has much trouble using it. Some existing problems include:
1. While there is one accessible Reddit client on IOS, the Reddit Enhancement suite isn't accessible, and there is nothing accessible for Android as far as I know. So finding an accessible way to add the functions of RES (tagging posters and filtering out websites are the two functions I wish for daily) would be useful.
2. Photo sharing on Facebook. Currently well over 90% of the facebook posts on my home newsfeed are images, and completely useless to me. Finding some way to make these more accessible, or creating an app that would hide them entirely, would make it much easier to keep up with my family and friends online. Could all photo posts be converted into text using data that already exists about the image? For example, "Joe posted a photo of himself with Bob and Alice taken in Time Square." Facebook already puts tags and geolocation data on photos, so that should be doable. Maybe use OCR to try and recover some of the images of text.
3. Pinterest is totally inaccessible. I don't know enough about this to even have any ideas for what, if anything, could be done about it.
4. An app that posts audio clips to Facebook the same way photos are posted to Facebook might be useful. A lot of blind people record audio of things for similar reasons that sighted people take photos. There are apps that allow you to post audio online, but as far as I know, none of them are as simple as just record and share. Also, none of them allow sighted friends to listen directly from the Facebook newsfeed, without any extra effort. An app like this would make it easier for me to share interesting things in my life with everyone on my friend list.
Those are just a few ideas off the top of my head.