Vim's new features allow some tricks with the display that sometimes allow more full-fledged editors to be implemented inside Vim itself.
Vim's new conceal feature allows the markup text to be hidden, and to show the rendered text instead.
Vim as a spreadsheet
display popup text, like Excel's "display comment"
These scripts are likely based on Vim's ballooneval feature, though that only works in GUIs. Alternative methods include amenu, and the completion feature.