Using Edmodo to post survey's as a means to gain opinion seems a good option. See my example below on my Edmodo Home page.This would be a great classroom set to intro a lesson--gather information, analyze the results. http://sbisd.edmodo.com/home
I also tried Stixy -- which is basically an electronic bulletin board for a sticky note...great for staff meetings, parking lot issues to come back to...check in techniques. I could also see it used in the classroom as a means to support Book Talk groups, they could post their comments on a page as they move through the chapters and then post for classmates to see. For a better review, see the link below from a fellow educator.