I must say, i'm so impressed with TeamViewer application. It's not an open source application, but it's available to Windows, Linux, and Macintosh platform. It's even available for Mobile platform, such as Android and iPad.
So, what does it do? Basically TeamViewer is an application that connects your computer anytime anywhere as long as you have Internet connection. Even if you are behind a proxy or firewalls, this application works out of the box without having it's user to configure anything. All you need is an account which can be registered instantly and it's free. You can then use this application to help other people (remote support), online presentation, and to control your computer remotely.
I have tried to use this application on Windows, Linux, and iPad and they all works perfectly just like what i need. It's really an impressive application.
Try it and prove it. I believe you will like this application as much as i do.