Free Android Phone app: https://play.google.com/store/apps/details?id=com.dropbox.android
Google Chrome app: https://chrome.google.com/webstore/detail/ioekoebejdcmnlefjiknokhhafglcjdl
Free iPad app: http://itunes.apple.com/us/app/dropbox/id327630330?mt=8&uo=4&at=10l6SU
Free iPhone app: http://itunes.apple.com/us/app/dropbox/id327630330?mt=8&uo=4&at=10l6SU
Free Mac program: https://www.dropbox.com/downloading?os=mac
Free Windows program: https://www.dropbox.com/downloading?os=win
Website: https://db.tt/dUahryRn
Free Android Phone app: https://play.google.com/store/apps/details?id=com.fusionprojects.edmodo
Free iPad app: http://itunes.apple.com/us/app/edmodo/id378352300?mt=8&uo=4&at=10l6SU
Free iPhone app: http://itunes.apple.com/us/app/edmodo/id378352300?mt=8&uo=4&at=10l6SU
Website: http://www.edmodo.com/
Google Chrome app: https://chrome.google.com/webstore/detail/edmodo/fpcdidgjjebefhmlhjlgnkahlimgaemc
Website: https://twitter.com/
Free iPad app: https://itunes.apple.com/us/app/id333903271?mt=8&at=10l6SU
Free iPhone app: https://itunes.apple.com/us/app/id333903271?mt=8&at=10l6SU
Free Android Phone app: https://play.google.com/store/apps/details?id=com.twitter.android
Free Android Tablet app: https://play.google.com/store/apps/details?id=com.twitter.android
Free Mac program: https://itunes.apple.com/us/app/twitter/id409789998?mt=12&uo=4&at=10l6SU
Free Android Phone app: https://play.google.com/store/apps/details?id=com.facebook.katana
Google Chrome app: https://chrome.google.com/webstore/detail/facebook-notifications/nmameahlembdcigphohgiodcgjomcgeo
Mozilla Firefox extension: https://addons.mozilla.org/en-US/firefox/addon/facebook-toolbar/
Free iPad app: https://itunes.apple.com/us/app/facebook/id284882215?mt=8&uo=4&at=10l6SU
Free iPhone app: https://itunes.apple.com/us/app/facebook/id284882215?mt=8&uo=4&at=10l6SU
Website: http://www.facebook.com/