function countdown_clock(year, month, day, hour, minute, format) {
    //I chose a div as the container for the timer, but
    //it can be an input tag inside a form, or anything
    //who's displayed content can be changed through
    //client-side scripting.
    html_code = '<div id="countdown"></div>';

    document.write(html_code);

    countdown(year, month, day, hour, minute, format);
}

function countdown(year, month, day, hour, minute, format) {
    Today = new Date();
    Todays_Year = Today.getFullYear() - 2000;
    Todays_Month = Today.getMonth();

    //Convert both today's date and the target date into miliseconds.                           
    Todays_Date = (new Date(Todays_Year, Todays_Month, Today.getDate(),
                                 Today.getHours(), Today.getMinutes(), Today.getSeconds())).getTime();
    Target_Date = (new Date(year, month - 1, day, hour, minute, 00)).getTime();

    //Find their difference, and convert that into seconds.                  
    Time_Left = Math.round((Target_Date - Todays_Date) / 1000);

    if (Time_Left < 0)
        Time_Left = 0;

    switch (format) {
        case 0:
            //The simplest way to display the time left.
            document.all.countdown.innerHTML = Time_Left + ' seconds';
            break;
        case 1:
            //More datailed.
            days = Math.floor(Time_Left / (60 * 60 * 24));
            Time_Left %= (60 * 60 * 24);
            hours = Math.floor(Time_Left / (60 * 60));
            Time_Left %= (60 * 60);
            minutes = Math.floor(Time_Left / 60);
            Time_Left %= 60;
            seconds = Time_Left;

            dps = 's'; hps = 's'; mps = 's'; sps = 's';
            //ps is short for plural suffix.
            if (days == 1) dps = '';
            if (hours == 1) hps = '';
            if (minutes == 1) mps = '';
            if (seconds == 1) sps = '';

            document.all.countdown.innerHTML = days + ' day' + dps + ' ';
            document.all.countdown.innerHTML += hours + ' hour' + hps + ' ';
            document.all.countdown.innerHTML += minutes + ' minute' + mps + ' and ';
            document.all.countdown.innerHTML += seconds + ' second' + sps;
            break;
        default:
            document.all.countdown.innerHTML = Time_Left + ' seconds';
    }

    //Recursive call, keeps the clock ticking.
    setTimeout('countdown(' + year + ',' + month + ',' + day + ',' + hour + ',' + minute + ',' + format + ');', 1000);
}