function add_fav($site){
$url=self.location.href;
if(navigator.userAgent.indexOf("MSIE") > -1){ //Internet Explorer
window.external.AddFavorite($url,$site);

}

else if((typeof window.sidebar == "object") && (typeof window.sidebar.addPanel == "function")){
window.sidebar.addPanel($site,$url,'');
}

/*else if(navigator.userAgent.indexOf("Opera") > -1){ //Opera
document.write('<a href="アドレス" rel="sidebar" title="サイト名">ブックマークに追加</a>');
}*/

else { //該当なし
void(0); //何もしない
}
}