I have heard wonderful things about edmodo and will definitely use this in the classroom for next year. At the beginning of this year, I did create an edmodo account but was unsure about how the students would feel about this product. The next class we have coming in is VERY familiar with the tool and teachers tell me that it is easy to start discussions. My only concern was monitoring how the students did on there and to make sure there was no cyber bullying. Teachers who use this tool tell me tat it is very easy to monitor because you can have an email sent to you search time someone creates a post. This way, I can have better control of the group. It is also great because it is private so the students are protected in that way as well.
Edmodo is great because you can use it for polls, assignment reminders, and of course, online discussion.
http://www.edmodo.com/home#/ (I was not sure how to create a link to my edmodo because it is private ..so I posted the link to the website.)
I have seen poll everywhere in use and it is lots of fun! The students have real ownership when they are able to use their own phones to interact with the room rather than the activotes (which they still enjoy). This is a great hook to have at the beginning of a lesson.