Jquery

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
 
<fieldset>
    <div><input type="checkbox" class="checkall"> Check all</div>
 
    <div><input type="checkbox"> Checkbox 1</div>
    <div><input type="checkbox"> Checkbox 2</div>
    <div><input type="checkbox"> Checkbox 3</div>
</fieldset>
 
 
<script>
$(document).ready(function(){
        $('.checkall').click(function () {
            $(this).parents('fieldset:eq(0)').find(':checkbox').attr('checked', this.checked);
        });
});
</script>

    <div><input type="checkbox" class="checkall" id="select_all"> Check all</div>
 
    <div><input type="checkbox" class="case"> Checkbox 1</div>
    <div><input type="checkbox" class="case"> Checkbox 2</div>
    <div><input type="checkbox" class="case"> Checkbox 3</div>
 
 
<SCRIPT language="javascript">
$(function(){
 
    // add multiple select / deselect functionality
    $("#select_all").click(function () {
          $('.case').attr('checked', this.checked);
    });
 
    // if all checkbox are selected, check the selectall checkbox
    // and viceversa
    $(".case").click(function(){
 
        if($(".case").length == $(".case:checked").length) {
            $("#select_all").attr("checked", "checked");
        } else {
            $("#select_all").removeAttr("checked");
        }
 
    });
});
</SCRIPT>

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
 
<select id="name" name="name">
<option value="" selected="selected">Please select...One Option</option>
<option value="Om">Om</option>
<option value="Jyoti">Jyoti</option>
<option value="Lal">Lal</option>
</select>
 <input type="text" class="phonnumber" name="phonenumber" value="" readonly="readonly">
<input type="text" class="phonnumber" name="phonenumber" value="" readonly="readonly">
<script type="text/javascript">
 $(document).ready(function(){
	$("#name").live("change", function() {
	  $(".phonnumber").val($(this).find("option:selected").attr("value"));
	});
});
</script>

You can pass select drop down value to one text box without using jQuery.
<script type="text/javascript">
    function explain(value){
      document.getElementById("fanpage_value").value=document.getElementById("list011").value;
    }
</script>
 
    <select id="list011" name="atk" class="but" onChange="explain(this)">
    <option value="1">1</option>
    <option value="2">2</option>
    <option value="3">3</option>
    </select>
 
 <form id="myform" method="post">What would you like to select
    <input id="fanpage_value" value="" disabled="disabled" class="but" size="50" />
      <input id="fanpage_value" value="" disabled="disabled" class="but" size="50" />
    <input type="submit" name="attack" value="POST!!" class="but" />
    </form>

<a onclick="parent.$.fn.colorbox.close();" href="http://www.phpmind.com" target="_top">PHPMIND.COM</a> This is good for normal site
 
<a onclick="parent.$.fn.colorbox.close();" href="http://www.phpmind.com" target="_parent">PHPMIND.COM</a> This works when we have Iframe like in facebook apps