Organizing Data Across a Heterogeneous Net?

angst_ridden_hipster asks: "Like many people, I have a bunch of machines I use regularly. These include Linux machines, BSD machines, a Mac OS X machine, and a Windows machine. These machines are on a number of networks. All have internet connectivity. Some of them are always powered on. A few of them are not. Obviously, I have a bunch of accounts. And, it goes without saying, I have a bunch of data. What are the best approaches to sharing data? I want to be able to securely access my home data while at work, and from one machine to another, etc. Opening ssh terminals is the approach I have traditionally used, but I'm beginning to wonder if some mirroring software (e.g., Unison) might be in order. It'd provide the function of backups, as well as guaranteeing availability. Would it be wiser to tunnel nfs over ssh? Or is there some better option? Assuming I actually start mirroring data across multiple machines, I'll need to organize it in a portable taxonomy. This is almost easy, since I use cygwin on the Windows machines, so I can assume a standard Unix-ish directory structure. But this gets more complicated when there are scripts or other code involved. What about application/platform-specific data? How do other people organize their data, anyway? Are there any useful standards? I'm hoping people will describe their approaches, and why they think they're (not) the best."