Задача: заменить граватар на произвольную картинку. Использую greasemonkey. Содержимое скрипта:
// ==UserScript==
// @name Подмена граватара
// @namespace http://www.w3.org/1999/xhtml
// @description Заменить граватар своей картинкой
// @include http://godville.net/*
// @include http://www.gravatar.com/*
// ==/UserScript==
/*
Кусок HTML с картинкой:
<img width="80" height="80" src="http://www.gravatar.com/avatar \
/6661da60460c881c8bd14363b0e6f5d8?rating=PG&size=80" \
alt="6661da60460c881c8bd14363b0e6f5d8?rating=pg&size=80">
*/
annoyingPic = "http://www.gravatar.com/avatar/6661da60460c881c8bd14363b0e6f5d8";
/* Картинка (серый квадрат) */
neutralPic = "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAFAAAABQCAMAAAC5 \
zwKfAAAAAXNSR0IArs4c6QAAAU1QTFRFgICAgYGBgoKCg4ODhISEhYWFhoaGh4eHiIiIiYmJioqK \
i4uLjIyMjY2Njo6Oj4+PkJCQkZGRkpKSk5OTlJSUlZWVlpaWl5eXmJiYmZmZmpqam5ubnJycnZ2d \
np6en5+foKCgoaGho6OjpKSkpaWlpqamp6enqKioqampqqqqq6urrKysra2trq6ur6+vsLCwsrKy \
s7OztLS0tbW1tra2t7e3uLi4ubm5u7u7vLy8vb29v7+/wMDAwsLCw8PDxMTExcXFxsbGx8fHysrK \
zMzMzc3Nzs7Oz8/P0NDQ09PT1NTU1dXV1tbW19fX2dnZ2tra29vb3Nzc3d3d3t7e39/f4ODg4uLi \
5OTk5ubm5+fn6Ojo6enp6urq6+vr7Ozs7e3t7+/v8PDw8fHx8vLy8/Pz9PT09vb29/f3+Pj4+fn5 \
+vr6/Pz8/f39/v7+////s3ceWwAAAAlwSFlzAAALEwAACxMBAJqcGAAAAAd0SU1FB9wGGwsCHxIb \
01wAAAAZdEVYdENvbW1lbnQAQ3JlYXRlZCB3aXRoIEdJTVBXgQ4XAAAAHUlEQVRYw+3BgQAAAADD \
oPlT3+AEVQEAAAAAAPAMGVAAAR9aiYoAAAAASUVORK5CYII=";
var images = document.getElementsByTagName("img");
var i = 0;
for (i = 0; i < images.length; i++) {
if (images[i].src == annoyingPic) {
images[i].src = neutralPic;
}
}