Bitbucket has a new feature,
http://blog.bitbucket.org/2015/03/18/snippets-for-teams-are-here-with-a-rich-set-of-apis/Interestingly, TiddlyWiki is one of the choices in the dropdown for a file type. Nothing happens yet, it simply reverts to plain text. Hopefully, it will support some subset of WikiText eventually, enough to replace Markdown.
I wonder if this could work for keeping community snippets. The number of contributors would have to be limited to 5 (to remain free), but everyone could read public snippets...?
--R.