これ

http://zuu9xi.sa.yona.la/3

個人的に好きで使わせていただいてるのですが（Operaでも動く），「ソース」というリンク先が消えているみたい。素敵なGreasemonkeyなので勝手ながら内容をここに転載させていただきます。（いいのかな...もしダメそうならお知らせ下さい）

// ==UserScript==
// @name           sa.yona.la identicon
// @namespace      http://zuu9xi.sa.yona.la/
// @description    sayonara identicon
// @include        http://sa.yona.la/*
// @include        http://*.sa.yona.la/*
//
// version: 0.0.2 2008-09-23(Tue) 18:56:15
//   changed style sheet of identicon
//
// ==/UserScript==

window.addEventListener("load", function () {
    var authors = getElementsByXPath('//p[@class="entry-note"]/a[1]', null)
    var identiconSize = 15
    var identiconStyle = {
        width: identiconSize + "px",
        height: identiconSize + "px",
        display: "inline-block",
        position: "relative",
        top: "-1px",
        right: "3px",
    }
    var addIdenticon = function (a) {
        var elem = document.createElement('img')
        elem.src = "http://identicon.relucks.org/" +
            a.textContent + "?size=" + identiconSize
        for (var key in identiconStyle) {
            elem.style[key] = identiconStyle[key]
        }
        a.parentNode.insertBefore(elem, a)
    }

    // add identicon to pagerized entry
    if (typeof window.AutoPagerize != "undefined") {
        window.AutoPagerize.addFilter(
            function (docs) {
                var authors = docs.map(function(d) {
                    return getElementsByXPath('.//p[@class="entry-note"]/a[1]', d)[0]
                })
                authors.forEach(addIdenticon)
            }
        )
    }

    // add identicon to current page entry
    authors.forEach(addIdenticon)
}, false)

// copied from autopagerize (http://userscripts.org/scripts/show/8551)
function getElementsByXPath(xpath, node) {
    var node = node || document
    var doc = node.ownerDocument ? node.ownerDocument : node
    var nodesSnapshot = doc.evaluate(xpath, node, null,
        XPathResult.ORDERED_NODE_SNAPSHOT_TYPE, null)
    var data = []
    for (var i = 0; i < nodesSnapshot.snapshotLength; i++) {
        data.push(nodesSnapshot.snapshotItem(i))
    }
    return data
}