On their own, boards are great for storing basic markdown text, however they can do more with optional features. Features are enabled by selecting one of the actions in the Actions dropdown menu. This will open a new email compose window. All you need to do is send that email as the sender who originally created the board and the feature will be enabled in a minute or two.
Commentable
Allow other users to comment on your board. You'll be notified of new comments in your daily email digest.
Votable
Each branch link is shown with a voting UI and they are automatically sorted by popularity. Creates a Reddit or Hacker News like board.
Forumable
Forumable turns your board into a forum. The board is votable and each branch is automatically commentable.
Bloggable
Turns your board into a blog. Each branch is a blog post and visitors can subscribe to your blog via RSS. Every blog post is automatically commentable. You'll be notified of new comments in your daily email digest.
Todoable
Turns your blog into a To do list with actual checkable items. You can "save" the checked state which will open an email compose window automatically moving items between "To Do" and "Complete."