I am using Mercurial Bitbucket to collaboratively work on LaTeX and markdown documents. For those kind of documents the diff viewer is not optimal as it - for good reasons - is optimised for code.
These kind of text documents tend to have very long lines (one paragraph) with small changes in them. For them rewrapping the text and highlighting which words (delimited by spaces) changed, is very helpful. See, for example, what meld does.
It would be great if there was an option to select a text-optimised-diff-viewer.