We're trying to move our project documentation process from Google Documents to a set of self-hosted Git repositories.
Text documents are Git-friendly enough, since we usually do not need any fancy formatting, we'll just convert everything to, say, multimarkdown with an option to embed LaTeX for complex cases.
But spreadsheets are quite different story... Is there a spreadsheed(-like) format that is friendly to version control systems (and, preferably, is as human-readable as Markdown)?
Obviously, Markdown flavors allow one to build static tables, but I'd like to be able to use stuff like
SUM() etc... (Note that CSV has the same problem.) No WYSIWYG is OK, but decent editor/tool support would be nice.
Update: Linux-friendly answers only, please. No MS Office stuff.