<head>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.min.js"></script>
</head>
<body>
<select name="" id="set_time">
<option value="0">выбрать</option>
<option value="-2">-2 часа</option>
<option value="-1">-1 часа</option>
<option value="0">0 часов</option>
<option value="+1">+1 час</option>
<option value="+2">+2 часа</option>
</select>
<div id="the_program">
<p>11:40 программа 1</p>
<p>12:40 программа 2</p>
<p>13:40 программа 3</p>
<p>14:40 программа 4</p>
</div>
<script>
$(function() {
var
$set_time = $('#set_time'),
$the_program = $('#the_program'),
number,
separator,
hour,
min_and_text;
$set_time.change(function() {
number = $(this).val();
$the_program.children().each(function(i, el) {
separator = $(el).text().indexOf(':'),
hour = $(el).text().slice('0', separator),
min_and_text = $(el).text().slice(separator);
$(el).text(+number + +hour + min_and_text);
});
});
});
</script>
</body>