twitter_embed_image.user.js

// ==UserScript==
// @name           twitter embed image
// @namespace      http://twitter.com/swdyh/
// @include        http://twitter.com/*
// ==/UserScript==

document.addEventListener("DOMNodeInserted", function(e) {
    var selector = 'a[href$=".jpg"], a[href$=".png"], a[href$=".gif"]'
    var elm = e.target

    if (elm.className == 'stream-item') {
        if (elm.querySelector(selector)) {
            var ei = elm.querySelector('.extra-icons')
            var span1 = document.createElement('span')
            span1.className = 'inlinemedia-icons'
            var span2 = document.createElement('span')
            span2.className = 'media photo'
            span1.appendChild(span2)
            ei.appendChild(span1)
        }
    }
    if (elm.className == 'component') {
        var as = elm.querySelectorAll(selector)
        for (var i = 0; i < as.length; i++) {
            var div = document.createElement('div')
            div.className = 'tweet-media'
            var img = document.createElement('img')
            img.src = as[i]
            var a = document.createElement('a')
            a.href = as[i]
            a.target = '_blank'
            a.appendChild(img)
            div.appendChild(a)
            elm.appendChild(div)
        }
    }

}, false)