cookies (#2):

<SCRIPT LANGUAGE="JavaScript">
<!--

var ar = new Array("<img src=\"img/cover2.jpg\" width=266 height=403 border=0 alt=\" #1\">",
"<img src=\"img/cover1.jpg\" width=266 height=403 border=0 alt=\" #2\">",
"<img src=\"img/cover0.jpg\" width=266 height=403 border=0 alt=\" #3\">");

function setCookie(name, value, expires, path, domain, secure) {
var curCookie = name + "=" + escape(value) +
((expires) ? "; expires=" + expires.toGMTString() : "") +
((path) ? "; path=" + path : "") +
((domain) ? "; domain=" + domain : "") +
((secure) ? "; secure" : "");
document.cookie = curCookie;
}

function getCookie(name) {
var dc = document.cookie;
var prefix = name + "=";
var begin = dc.indexOf("; " + prefix);
if (begin == -1) {
begin = dc.indexOf(prefix);
if (begin != 0) return null;
} else
begin += 2;
var end = document.cookie.indexOf(";", begin);
if (end == -1)
end = dc.length;
return unescape(dc.substring(begin + prefix.length, end));
}
var expDays = 30;
var now = new Date();
now.setTime(now.getTime() + (expDays * 24 * 60 * 60 * 1000));
var num = getCookie("ChangeImage");
num = (num && (parseInt(num) < ar.length - 1)) ? (parseInt(num) + 1) : 0;
setCookie("ChangeImage", num, now);

document.write(ar[num]);

// -->
</script>


ciao !