Edit in JSFiddle

(function($) {

    $.fn.dynamo = function() {

        return this.each(function(i, v) {

            var delay = parseInt($(v).attr('data-delay')) || 3000;
            var speed = parseInt($(v).attr('data-speed')) || 350;

            var lines = $(v).attr('data-lines').split(',');

            // wrap the original contents in a span
            $(v).html($('<span></span>').text($(v).text()));

            // grab the width of the span
            var max = $(v).find('span:eq(0)').width();

            // for each item in data-lines, create a span with item as its content
            // compare the width of this span with the max
            for (var k in lines) {
                var span = $('<span></span>').text(lines[k]);
                $(v).append(span);
                max = Math.max(max, $(span).width());
            }

            // replace all the spans with inline-div's
            $(v).find('span').each(function(i, el) {
                var s = $(el).remove();
                var d = $('<div></div>').text($(s).text());
                $(d).width(max);
                $(v).append(d);
            });

            // set the height of the dynamo container
            var height = $(v).find('>:first-child').height();

            // style
            $(v).width(max).height(height);
            $(v).css({
                'display': 'inline-block',
                'position': 'relative',
                'overflow': 'hidden',
                'vertical-align': 'bottom',
                'text-align': 'left'
            });

            // manually center it if we need to
            if ($(v).attr('data-center')) $(v).css('text-align', 'center');

            // now, animate it
            var transition = function() {
                $(v).find('div:first').slideUp(speed, function() {
                    $(v).append($(this).remove().show());
                });
            };

            setInterval(transition, delay);
        });
    };



})(jQuery);

$('.dynamo').dynamo();

body {
    background-image: url('../images/cross_scratches.png');
}

#content {
    background-color: #fff;
    width: 900px;
margin-left: auto;
    margin-right: auto;
    padding: 35px;

    position: relative;
    top: -50px;

    -moz-box-shadow: 0 0 8px 8px #aaa;
    -webkit-box-shadow: 0 0 8px 8px #aaa;
    box-shadow: 0 0 8px 8px #aaa;
}

#welcome-mat {
    text-align: center;
    margin: 50px auto 0 auto;
}

#welcome-mat h1 {
    font-size: 90px;
    line-height: 100px;
}

#welcome-mat p {
    margin-top: 10px;
    font-size: 30px;
    font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
    font-weight: 300;
    line-height: 35px;
}

#welcome-mat #buttons {
    margin-top: 25px;
}

p {
    font-size: 120%;
    line-height: 20px;
}

h1 {
    margin-bottom: 20px;
}

.example {
    height: 90px !important;
    margin: 15px 0;
}

div.example {
    -webkit-border-radius: 4px;
    -moz-border-radius: 4px;
    border-radius: 4px;

    padding: 8px;

    border: 1px solid #aaa;
}

code {
    color: #222;
}

li {
    line-height: 30px;
}

.foot {
    font-size: 100%;
    float: right;
}

<p>今日の天気は<span class="dynamo" data-lines="あめ,曇り,微妙" data-delay="2000">晴れ</span>です。私は<span class="dynamo" data-lines="大阪出身,新潟出身,帰りたい">東京出身</span>です。</p>
<p>リンクも貼れる→<a href="https://www.google.co.jp/webhp?hl=ja&tab=ww"><span class="dynamo" data-lines="グーグル,ごおｇぇ" data-delay="1000" data-speed="100">Google</span></a></p>