Drafts 4 is out as a Universal app. I’ll leave it to the experts to offer the full review, and just mention that there’s a very cool new feature in it: JavaScript-based text modification actions.
You can use JavaScript to modify text selections and entire documents, and encapsulate them in modules that you can add to the custom keyboard row. Check out the existing Keyboard Extensions for ideas.
I’m excited about this because it’s going to be relatively easy to port the tricks I built for my old WordPress plugin, Markdown QuickTags. I’m working on a few right now, and will publish them as I finish them.
Check out the Agile Tortoise site for more info, and grab Drafts 4 for iPhone and iPad in the App Store for $4.99 US.