What other features do you want?

Suggestions:

• Profile pages for users (enter user's name or details, have it display alongside posts).
• Post/Comment history for individual users (on their profile page?).
• Easy user profile pictures with Gravatar.
• Add login options with Omniauth, including Twitter, Facebook, Github, Google, and more.
  • Check out the Devise documentation for integrating with Omniauth.
• Fiddle with the layout of the show page so it doesn't look bad. If it looks bad. It probably looks great.
• Perhaps fancier post markup with Markdown or something similar.
• Deploy to Heroku and send your message board to all your friends!

...and that's that! Good luck! Make more things! Come back again!