[farkas]

As the CEO of Atlassian, I'm obviously biased, but you should really check out Confluence. With 10s of thousands of companies using it for this exact purpose we have deep experience solving this type of problem.

Confluence provides templates for things like retros. It allows embedding of files, videos. Concurrent editing currently being rolled out.

Big thing with collaboration is ensuring things are public by default, which is not the case with Google docs and others.

You need it to be WYSIWYG for non-technical people to use, which rules out GitHub Wiki and others of that ilk.

Happy to answer any other questions about usage if you try it out.

Scott

[brianjking]

Confluence is great, it just gets incredibly expensive rather quickly. Self-hosting the $10 version is probably the best route, however, it's fairly resource intensive and seems rather cumbersome (damn you, java) if you have issues.

[mrits]

I've recently discovered Markdown-plus. It is so much nicer (for me) to use than Confluence. It uses mermaid for it's diagramming. The ability to generate my diagrams from code like markdown is huge for me. I can share everything through github with my team like I do code. I paid $15 for the OS X app, but I'm pretty sure it's all free in other forms.