There's a document tagging system in Taskpaper.iPhone that Jesse said
he will port over to WR.iPhone the next time he updates it. I'm hoping
when he pushes out the iPad version. Which I'm also hoping is soon.
In the mean time, I've been using a combination of file naming
conventions, (i.e. title.chapter.version.txt) that I call up with the
search feature and the Sort By Modified setting. It ain't perfect, but
it's better than nothing.