Dingtone - Dingtone is a free call and texting application for making unlimited calls and text messages to any number at the moment registered in any part of the world by any cellular company.
Clever - syncing between education applications for K-12 schools
Textnow.com - It lets you text your friends, aka my only source of happiness
PowerSchool - PowerSchool provides a K-12 education technology platform for operations, classroom, student growth, and family engagement.
FluffyChat - Open. Nonprofit. Cute ?
Claroline - Claroline is a collaborative eLearning and eWorking platform.