Screenleap

Screenleap is an online service that allow users to share their screen with others. You need to send to your viewers a link generated by the program or a secret code. Only people who knows exactly that code or link are able to view your screen.
 
In the same way, you can view a remote desktop of a computer from another location. Only internet connection is required.
 
Multiple viewers are allowed and this program features also audio conference options.
 
The free version is limited to 2 hours per day and data is no encrypted, but may be useful for a simple screen sharing with a friend or a person that can provide support from distance based on what is viewing on your screen.