BeamYourScreen

This program is an alternative of Teamviewer. It works almost the same, you need an id nummer from another computer to make connction. You can use this program as portable so save it to your usb stick to run it from every device. You can chat while connecting and also file transfer and clipboard is possible.

The most interesting thing here is that you can connect to a computer with more people simultaneously. You can use it on Linux, Mac or Windows systems.