code:

// ==UserScript==
// @name         SASmilieSearch
// @namespace    forums.somethingawful.com
// @version      0.1.5
// @description  Smilie autocomplete search box
// @author       Me
// @match        [url]http://forums.somethingawful.com/misc.php?action=showsmilies[/url]
// @match        [url]https://forums.somethingawful.com/misc.php?action=showsmilies[/url]
// @grant        none
// ==/UserScript==

(function() {
    'use strict';
    $('h2').after('<input type="text" id="box" />');

    $('#box').autocomplete({
        source: $.map($('li.smilie'), function(el) {
            var code = el.textContent.replace(/\n/g, ''),
                img = el.lastElementChild.cloneNode();
            return {
                label: code + ' ' + img.title + ' ',
                value: code,
                img: img
            };
        })
    }).data('ui-autocomplete')._renderItem = function(ul, item) {
        return $('<li>')
            .attr('data-value', item.value)
            .append(item.label)
            .append(item.img)
            .appendTo(ul);
    };
})();