Allow (slightly) more HTML
This engine does allow a subset of HTML, but it's extremely limited. This makes some sense for a QA site, but not being able to use either tables or divs will be really annoying for a blog/wiki, and rules out user-created WP style infoboxes, sortable tables of data, and a lot of other things. I imagine you'd need to alter the whitelist to allow the tags (and certain safe attributes?), perhaps ordinary title would check implementation/advise? And for sortable tables you'd need to pick some table sorting .js. Alternatively there are extensions of markdown which allow tables, but that seems likely to be more complex to implement.
There are other tags which would be nice to have access to such as