Skype is a great tool for seeing classes that you are collaborating with! Students can interact with one another in realtime as well as face to face and not have all collaboration done over documents or written communication.
Wordpress has been used within middle school to college courses to build empathy by creating sites for or about movements, people, and even communities. This is a tool that is a little above an elementary level, but fantastic for middle school aged students all the way to college students. It is a great blogging site that allows students to have their voices and perspectives heard and connect with people all over the world.
Google Earth is a great tool to explore things that you may be learning about. It truly can take your students on a virtual field trip, anywhere in the world. While it doesn't have guided tours or the ability to go inside of these places, it is awesome for providing context and a visual picture of what you could be talking about within global education and empathy development.
ePals is a great tool to access other classrooms without having to go out of your way to find someone to connect with. This is a tool that is used all over the world by educators. It is essentially a social network of educators who are looking to connect with other classrooms and engage their students in a dialogue with one another.
Youtube can be a great resource for things that have already been created to bring into your classroom to challenge students perspectives and open their eyes to varying perspectives. In building empathy it is imperative that students have access to things that push them in their thinking that is not just their teacher, and youtube is another platform which allows for that to happen.
If you have never checked out Project Zero out of Harvard University, do yourself a favor and immediately go to their site. This is a phenomenal resource with lesson plans, engaging activities, and even resources for developing a digital learning life. This is one of the best global education and technology resources accessible for free for teachers.
Google docs is a very easy and accessible way to collaborate with others around the world. This is a tool that students and educators can both utilize. Personally, I have used this to plan lessons with colleagues and have students use this as their platform for communicating with other students. This is also a great tool when students are not in the same time frame to see what others have changed, added to, or simply just written.