Poll everywhere is excellent for when those little Active votes don't function like you want them to and it adds the novelty of the tool. Edmodo is awesome for the students as well as teachers to keep,up with each other. Our entire campus is now on line with Edmodo as well as Skype. Google docs are being used all a cross campus and I think that students can use it on campus as well as those who have access at home.
Google. Docs has a presentation for helping students remember the rules for integers!