Social Networking for Dietitians

My kids introduced me to Facebook but to be honest, I've not spent the time or effort that they do to interact there. However, that experience did make me wonder how professionals can use social networking to communicate. I found Linked In and have a profile there (you can view it here). I also created a network group for dietetics professionals there. While that group is growing, there seems to be very little communication going on. I also belong to a network for Health IT professionals that seems to have quite a lot of discussion. That makes me wonder how RDs communicate?