Done Tags in NVAlt
This is some really high quality work and attention to detail. If you add the tag "@done" at the end of a line in NVAlt, the text is automatically displayed with a strikethrough line, a la TaskPaper. It's not reformatted. It's still just plain text. But NVAlt displays it as if it was formatted with a strikethrough.
Also, don't forget the double brackets automatically create links to other notes.