I have to turn out some network topology maps for very large networks. I'd like the format for the maps to be something other people can also edit and contribute to regardless of what software I'm using on my Mac to build them. I don't mind spending money on my end for software, but I can't require that my clients spend any money. I also can't promise my clients are also using OS X -- they could be running Linux or Windows.

Is there a best software application on OS X for producing maps that I can share with other, non-OS X, users?

Is there a best format for sharing topology maps that I should use when exporting the maps to disk?