I didn't have any real use cases in mind when I made it, I just wanted to see if it was possible.

In theory you could use it to demonstrate the underlying Markdown for some HTML, but unfortunately I haven't been able to figure out how to make the CSS ::before and ::after content user-selectable[0], so you wouldn't be able to copy it back out to make a simple HTML-to-Markdown converter.

[0] http://stackoverflow.com/questions/19914349/how-can-i-make-g...

the table stuff doesnt work too well either, understandably. if you actually want to do conversion though, check out reMarked.js [1], disclaimer: mine. it's not too heavy, either.

[1] https://github.com/leeoniya/reMarked.js

Yes.

I often find myself using http://markdown-here.com/ to compose an email, and then wanting to get back at the source to send another, slightly modified email, or to insert into a README.md.

This will make my life a lot easier. Just need to package it up into a nice browser toolbar button.

no, because you can't copy paste the tags. they're just visual sugar that isn't actionable.

Not super practical, but I use [something similar on my site](http://makenosound.com/2012/10/07/going-paperless.html) as a stylistic thing.

Complex tables? You could use a WYSIWYG HTML editor to quickly create them, and then use this to convert to MD. That's the only thing I can think of.