At the risk of possible overlap with this (9-month-old) question
what is the best desktop application now for running MathJax in the classroom.
I can't depend on having a connection to the web, so I'm seeking a stand-alone application. To be clear, I'd like to type as I talk and have the students see the typeset mathematics with as small a delay as possible. (An application's waiting for the ends of paragraphs might be a deal breaker.)