it'd be fairly easy to make one, but i imagine it would have limited utility since the entire content of the page is rarely what you want. how would you go about selecting which portion you're interested in? also, i'm not certain a bookmarklet would have direct clipboard access due to security, i could be wrong tho.

feel free to open up an issue on github to discuss the idea and implementation details further.

This may have changed in the last few years, but I believe you can simply do "window.getSelection()" in your bookmarklet to access the currently selection for Firefox/WebKit browsers.

might be worth trying. however, i'm still not convinced the presented use-case would be useful rather than just cool.

Sadly you're almost certainly right. Most of the places I could see wanting to reverse-engineer the displayed HTML into Markdown are actually sites using their own hackish, inconsistently rendered output. You'd end up needing per-site tweaks and that'd kind of render the whole thing unworkable and pointless.