A bookmarklet for grabbing just a piece of a web page and converting it to Markdown using heckyesmarkdown.com.

Bullseye.js

// version 0.5
// Uses nvALT. 
// Not using remote/external loading because it is often blocked by allowed-origin.
// Now serves under HTTPS.

// version 0.4
// Bugfix for Firefox
//
// Bullseye 0.3
// Add escape key to cancel
// Only use the first class when constructing path, potentially avoid dynamically-added classnames
// Allow bookmarklet to be called with "window.bullseyeShowFrame=0" at the beginning to return just raw text
//
// Version 0.2
// Resolves relative urls
// removes Twitter intent links
// tries to update lazy loaded image urls
// loads from raw source, with fallback for dynamically-loaded content
(function () {
	function callback() {
		(function ($) {
			var jQuery = $, $els = $("div,table,article,section,aside");
			$('#loadingp').fadeOut("fast", function () {
				$(this).remove();
			});
			$els.on("mouseover mouseout click", function (a) {
				a.stopPropagation();
				a.type === "mouseover" ? $(this).css({
					outline: "1px solid rgb(194, 130, 148)"
				}).addClass("mkhovered") : $els.css({
					outline: "none"
				}).removeClass("mkhovered");
				if (a.type === "click") {
					a.preventDefault();
					$(".mkhovered").css({
						outline: "none"
					}).removeClass("mkhovered");
					var $container = $(this);

					var elpath = [], $parents = $container.parentsUntil("body").add($container);
					$parents.each(function(i,n) {
						var index = $(n).index();
						index = (index < 2) ? ":first" : ":nth-of-type("+(index-1)+")";
						var tag = n.tagName.toLowerCase();
						if ($(n).attr("id") !== undefined) {
							elpath.push("#"+$(n).attr("id"));
						} else if (n.className !== "") {
							elpath.push(tag+"."+n.className.split(" ")[0]+index);
						} else {
							elpath.push(tag+index);
						}
					});
					var loadpath = window.location.pathname+" "+elpath.join(" ");
					// console.log(loadpath);
					// return;
					$("<div>").load(loadpath, function() {
						var raw = this;
						if ($(raw).text() === "") {
							raw = $("<div>").append($container.html()).get(0);
						}
						$(raw).find('a[href*="twitter.com/intent"],a[href*="app.net/intent"]').remove();
						$(raw).find("a,img").each(function(){
							var el = this, $el = $(el), attr = el.tagName === "A" ? "href" : "src";
							if (el.tagName === "IMG") {
								if ($el.data("original") !== undefined) {
									$el.attr(attr,$el.data("original"));
								}
							}
							if (!/^http/.test($el.attr(attr))) {
								if (/^\//.test($el.attr(attr)))
									var baselink = window.location.protocol + "//" + window.location.hostname;
								else
									var baselink = window.location.href.split("/").slice(0,-1).join("/") + "/";
								$el.attr(attr, baselink + $el.attr(attr));
							}
						});
						var $form = $("<form>").attr("method", "post").attr("action", "https://heckyesmarkdown.com/go/")
						.append($("<input name=html>").val(encodeURIComponent(raw.innerHTML)))
						.append($("<input name=read>").val("0"))
						.append($("<input name=output>").val("nv"))
						.append($("<input name=showframe>").val("0"))
						.appendTo('body');
						$form.submit(function(event){
						    $.ajax({
						      url: $form.attr('action'),
						      type: $form.attr('method'),
						      data : $form.serialize(),
						      success: function(e) {
						      	location.assign(e);
						      }
						    });
						    event.preventDefault();
						});
						$form.submit();
					});
				}
			});
			$(document).bind("keyup",function(e) {
				if (e.keyCode === 27) {
					$els.unbind("mouseover mouseout click");
					$(".mkhovered").css("outline","none").removeClass("mkhovered");
					$(document).unbind("keyup");
				}
				return true;
			});
		})(jQuery.noConflict(true))
	}
	var s = document.createElement("script");
	s.src = "https://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js";
	if (s.addEventListener) {
		s.addEventListener("load", callback, false)
	} else if (s.readyState) {
		s.onreadystatechange = callback
	}
	document.body.appendChild(s);
})();

Bullseye.min.js

!function(){function t(){!function(t){var e=t("div,table,article,section,aside");t("#loadingp").fadeOut("fast",function(){t(this).remove()}),e.on("mouseover mouseout click",function(a){if(a.stopPropagation(),"mouseover"===a.type?t(this).css({outline:"1px solid rgb(194, 130, 148)"}).addClass("mkhovered"):e.css({outline:"none"}).removeClass("mkhovered"),"click"===a.type){a.preventDefault(),t(".mkhovered").css({outline:"none"}).removeClass("mkhovered");var n=t(this),o=[],i=n.parentsUntil("body").add(n);i.each(function(e,a){var n=t(a).index();n=2>n?":first":":nth-of-type("+(n-1)+")";var i=a.tagName.toLowerCase();void 0!==t(a).attr("id")?o.push("#"+t(a).attr("id")):""!==a.className?o.push(i+"."+a.className.split(" ")[0]+n):o.push(i+n)});var r=window.location.pathname+" "+o.join(" ");t("<div>").load(r,function(){var e=this;""===t(e).text()&&(e=t("<div>").append(n.html()).get(0)),t(e).find('a[href*="twitter.com/intent"],a[href*="app.net/intent"]').remove(),t(e).find("a,img").each(function(){var e=this,a=t(e),n="A"===e.tagName?"href":"src";if("IMG"===e.tagName&&void 0!==a.data("original")&&a.attr(n,a.data("original")),!/^http/.test(a.attr(n))){if(/^\//.test(a.attr(n)))var o=window.location.protocol+"//"+window.location.hostname;else var o=window.location.href.split("/").slice(0,-1).join("/")+"/";a.attr(n,o+a.attr(n))}});var a=t("<form>").attr("method","post").attr("action","https://heckyesmarkdown.com/go/").append(t("<input name=html>").val(encodeURIComponent(e.innerHTML))).append(t("<input name=read>").val("0")).append(t("<input name=output>").val("nv")).append(t("<input name=showframe>").val("0")).appendTo("body");a.submit(function(e){t.ajax({url:a.attr("action"),type:a.attr("method"),data:a.serialize(),success:function(t){location.assign(t)}}),e.preventDefault()}),a.submit()})}}),t(document).bind("keyup",function(a){return 27===a.keyCode&&(e.unbind("mouseover mouseout click"),t(".mkhovered").css("outline","none").removeClass("mkhovered"),t(document).unbind("keyup")),!0})}(jQuery.noConflict(!0))}var e=document.createElement("script");e.src="https://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js",e.addEventListener?e.addEventListener("load",t,!1):e.readyState&&(e.onreadystatechange=t),document.body.appendChild(e)}();