like_everywhere.user.js

// ==UserScript==
// @name           LikeEverywhereAtBottom
// @namespace      http://blog.katsuma.tv/
// @include        http://*
// @include        https://*
// ==/UserScript==

(function (){
    if(unsafeWindow.self != unsafeWindow.top){
        return;
    }
    var wrapper = document.createElement('div');
    wrapper.style.cssText = 'position: fixed; bottom: 20px; left: 5px; width:200px;';
    wrapper.innerHTML = '<iframe src="http://www.facebook.com/plugins/like.php?href=' + encodeURI(location.href) + '&amp;layout=standard&amp;show_faces=true&amp;width=450&amp;action=like&amp;colorscheme=light&amp;height=80" scrolling="no" frameborder="0" style="border:none; overflow:hidden; width:450px; height:80px;" allowTransparency="true"></iframe>';
    document.body.appendChild(wrapper);
})();

function log(s){
    unsafeWindow.console.log(s);
}