The web site Patients Like Me is a great place for you to gain access to a network with the specific conditions you are looking for. Also, you might want to try various professional societies to tap into the network of providers treating the individuals with the specific health conditions. For instance, if you are looking for people with heart disease, look at the American College of Cardiology and see what they offer for patient support in terms of networks, blogs, etc. Also, Linkedin in and Facebook, of course, have groups for people with specific health conditions.