I’m quite happy to see a new Habari user, Dylan, over at Trifold Design, has created a Textile plugin for Habari. I too use many of the same tools Dylan does, and find myself using that markup more and more, even in email and on IRC (though, embarrassingly I didn’t realize it was actually Textile).
I haven’t actually tested the plugin yet, though it did install fine, and it’s a .5 release, so I assume the author has vetted it himself.
Also, welcome to the community Dylan, it’s always great to see new people join in.
For those that are looking for other markup plugins, you might look at Matt Read’s Markdown plugin as well.