Jetbrains IDE's (IntelliJ, WebStorm, PyCharm, etc) have a killer keyboard command for incrementally selecting greater ranges of text.
The first invocation selects the word at the caret, and then each subsequent invocation expands the selection according to the natural hierarchy of the particular programming language being edited. Generally it expands along the lines of word, statement, expression, block, function, class and so on.
It's really handy when you are editing a doc that has some kind of natural hierarchy. This would work well in MD: for instance, expanding from word, to list item, to entire list, and then expanding incrementally up the header chain.