- Set a cookie and let the poster edit/delete the page after it's published. They will make typos, mess up the formatting, post while drunk, etc.
- Markdown formatting. You need at least bold and italics. You could even have a small toolbar. I don't think the editor needs to be super minimal, just the viewer.
- Make sure the branding and links at the bottom are visually distinct from anything the user could enter. Maybe give it a grey background or invert it or something. Fixed positioning is also an option, but might be too annoying.
- Remove the Feedback tab from the viewer.. really spoils the aesthetic.