[Dilettante_Pro]

Имя: <input type="text" id="lastName" value="Вася">
<input type="button" id="set" value="Записать">
<input type="button" id="get" value="Прочитать">
<script>
set.onclick = function() {
    var old = localStorage.getItem('name_'), 
          arr;
    (old && old.length > 0)?  arr = new Array(old):  arr = []; 
    arr.push(lastName.value);
    localStorage.setItem('name_', arr.join(","));
}
get.onclick = function() {
    alert(localStorage.getItem('name_'));
 }
</script>