I have an adviser that hates TeX and would prefer to provide comments but no edits. I would love to see an environment where I could both collaborate with other students on writing the TeX, but also have the ability to enable peer review with Crocodoc-style [1] commenting and annotation.

[1] https://crocodoc.com/

I'd love to have replayable version history (with comments on versions like mateja suggested). If it could integrate with github as a storage backend, it would be awesome :)

Dropbox integration!