The ability to quickly and easily produce HTML5 presentations from simple text markup is something that already exists in emacs. But you knew that.
Org-mode is a do-it-all mode for taking notes and lots of other things. People use it to maintain their calendars, to write todo lists, to organize thoughts.
* More on Org-mode - In org, you format your notes in a simple markup - Use asterisks to mark slide headers - dashes to mark bullets - this is a sub-bullet - just indent to get the hierarchy - Here is the source code for THIS SLIDE