Added Greasemonkey userscript for the same thing

userscript/script.user.js

@@ -0,0 +1,84 @@
+// ==UserScript==
+// @name Word To Word Replacer
+// @description Replaces words predetermined by a wordlist
+// @version 1.0
+// @namespace http://boxmein.x10.mx/
+// @include *
+// @run-at document-end
+// ==/UserScript==
+
+// ctrl+f "var replacements"
+
+// just a mash together of userscript stuff and cloud-to-butt stuff
+
+// http://wiki.greasespot.net/Content_Script_Injection
+function contentEval(source) {
+  if ('function' == typeof source) {
+    source = '(' + source + ')();'
+  }
+  var script = document.createElement('script');
+  script.setAttribute("type", "application/javascript");
+  script.textContent = source;
+  document.body.appendChild(script);
+  document.body.removeChild(script);
+}
+
+
+
+contentEval(function() {
+
+
+	var replacements = [
+		// a list of objects with keys from and to, signifying what to find and what
+		// to replace the string to
+		// the from key can also be a Javascript compatible (perl compatible) regex
+		// {"from": "cloud", "to": "butt" },
+		{"from": /[aeiou]/ig, "to": "o"}
+		// ...
+	];
+
+	// I stole this 101% from https://github.com/panicsteve/cloud-to-butt/blob/master/Source/content_script.js
+	function walk(node) 
+	{
+		// I stole this function from here:
+		// http://is.gd/mwZp7E
+
+		var child, next;
+
+		switch ( node.nodeType )  
+		{
+			case 1:  // Element
+			case 9:  // Document
+			case 11: // Document fragment
+				child = node.firstChild;
+				while ( child ) 
+				{
+					next = child.nextSibling;
+					walk(child);
+					child = next;
+				}
+				break;
+
+			case 3: // Text node
+				handleText(node);
+				break;
+		}
+	}
+
+	function handleText(textNode) 
+	{
+		var v = textNode.nodeValue;
+
+		for (var i=0, r=replacements; i<r.length; i++) {
+			v = v.replace(r[i].from, r[i].to);
+		}
+
+		textNode.nodeValue = v;
+	}
+
+	// notifying any stronger would be disastrously annoying
+	if (replacements.length == 0) 
+		console.log('Configure replacements in script source code');
+
+	walk(document.body, handleText);
+});