I'm not sure if I've worded this question well.
I have family members, friends and clients scattered all over the world who rely on me for technical advice. Directing them over email or the telephone feels a little like I have had my eyes cut out and my hands chopped off and I don't speak the same language.
I would like to be able to view and control their desktops remotely with minimal effort on their part (lets assume they're all as capable with computers as a common cold), without exposing them to any serious security hazards. Some of my clients travel frequently, and often only find that things stop working when they are working at locations outside their offices, so having forwarded ports is not something I can rely on.
Some of the computers run Windows, some OS X and some Linux. I need to at least be able to control the OS X and Windows ones. Some kind of way to manage a list of the connections would be helpful too. It would be incredibly useful if I could do it from my iPhone, but I realise I'm probably pushing it. My computer is a mac running snow leopard.
Is there a straightforward way to do this? I'm not opposed to installing things on their machines, but the less nitty-gritty config stuff they have to do the better.
I would prefer a solution that makes use of freeware as I'm pretty skint.