I second the desire for markdown hinting. I've been using this for a while via Chrome for writing and it's very good, very happy that it detects when there is a newer version in Dropbox (don't know about Drive, don't have that connected. Just missing that one piece for me.
I mean, since this is single window (so no side-by-side source and compiled) that when you surround with asterisks, the asterisks are still visible, but the whole word is italicised. it is often performed by markdown syntax highlighters - if you're on OS X, try textmate 2 with the extension ".md" to see what I mean (it makes a wonderful job of semi-previewing my octopress blog entries.)
