Yeah, agreed about vimwiki. I've been using it as a knowledge base for years, for quick snippets, ideas, article/book synopsis and notes etc. And the fact that you can interlink them conveniently is a big upside.

A question about vimwikigraph while I'm at it - does it work with the markdown syntax? For instance, VimwikiCheckLinks doesn't work for me at all. And the HTML export isn't supported, although that's a minor issue since there are a million tools which can parse markdown into anything.