Hi tjmoosh,
This is the entire code with the changes.Please check it and know whether thats the requirement.Hope that works. :)

[CODE]
<body>
<div>
Newspaper<br>
<select id="newspaper" NAME="newspaper" style="width:350px" onchange="disable(this)">
<option value="null"></option>
<option value="news1">news1</option>
<option value="other">Other</option>
</select>
<br><br>

    Magazine/Trade<br>
    <select id="magazine" NAME="magazine" style="width:250px" onchange="disable(this)">
        <option value="null" ></option>
        <option value="magazine1">magazine1</option>
        <option value="other">Other</option>
    </select>
    <br><br>

    Web<br>
    <select id="web" NAME="web" style="width:250px" onchange="disable(this)">
        <option value="null" ></option>
        <option value="web1">web1</option>
        <option value="other">Other</option>
    </select>
    <br><br>

    TV<br>
    <select id="tv" NAME="tv" style="width:250px" onchange="disable(this)">
        <option value="null" ></option>
        <option value="tv1">tv1</option>
        <option value="other">Other</option>
    </select>
    <br><br>

    Radio<br>
    <select id="radio" NAME="radio" style="width:250px" onchange="disable(this)">
        <option value="null" ></option>
        <option value="radio1">radio1</option>
        <option value="other">Other</option>
    </select>
    <br><br>
    Other
    <input name="OtherOutlet" id="OtherOutlet" type="text" size="50" maxlength="255" disabled="true"><br /><br />
    <input type="button" value="Reset" onclick="enableAllSelect()">
</div>

</body>
<script type="text/javascript">
function disable(element)
{
var selectArrayId = ["newspaper","magazine","web","tv","radio"];
var excludeId = element.id;
var selectValue = element.value;

    if(selectValue == "other")
    {
        document.getElementById("OtherOutlet").disabled=false;
    } 

    for(x in selectArrayId)
    {
        if(selectArrayId[x] != excludeId)
        {                                       
            document.getElementById(selectArrayId[x]).disabled=true;
        }
    }
}

function enableAllSelect()
{
    var selectArrayId = ["newspaper","magazine","web","tv","radio"];

    for(x in selectArrayId)
    {
        document.getElementById(selectArrayId[x]).disabled=false;
        document.getElementById(selectArrayId[x]).value="null";
        document.getElementById("OtherOutlet").disabled=true;
        document.getElementById("OtherOutlet").value="";
    }
}

</script>
[/CODE]

tjmoosh commented: Very helpful! +1

Hi try this...

[CODE]
<head>
<script type="text/javascript" src="http://code.jquery.com/jquery-1.4.4.min.js"></script>

<script type="text/javascript">

$(document).ready(function(){
    $('#myTextBox').click(function(){
        $('#myTextBox').val("");
    });

    $('#myTextBox').blur(function(){
        var currentText = $('#myTextBox').val();
        if(currentText == "")
        {
            $('#myTextBox').val("Enter text");
        }
    });
});     
</script>

</head>

<body>
<input type="text" id="myTextBox" value="Enter text">
</body>
[/CODE]

minimogul commented: Just Awesome no need to say anymore. +1

This would enable all the select options..
Put this Reset button in the body:
[CODE]
<input type="button" value="Reset" onclick="enableAllSelect()">
[/CODE]

In the script add this function:
[CODE]
function enableAllSelect()
{
var selectArrayId = ["newspaper","magazine","web","tv","radio"];

    for(x in selectArrayId)
    {
        document.getElementById(selectArrayId[x]).disabled=false;
    }
}

[/CODE]

Think this fixes the IE issue..please check..

[CODE]
<script>
function setOptions(chosen)
{
var selbox = document.form1.Iunit;
selbox.options.length = 0;

if (chosen == " ") {
selbox.add(new Option('Please select one of the options above first',' '));

}

/ New Option forces browsers to use an older DOM model which fails in IE.
Use add method.Also it takes 2 parameters, so will have to use null for browsers other than IE since IE won't take null.
/

if (chosen == "1") {
try{
selbox.add(new Option('Milimeters','mm'));
selbox.add(new Option('Meters','m'));
selbox.add(new Option('KiloMeters','Km'));
selbox.add(new Option('Feet','f'));
selbox.add(new Option('Yards','y'));
selbox.add(new Option('Miles','mi'));
}
catch(err)
{
selbox.add(new Option('Milimeters','mm'),null);
selbox.add(new Option('Meters','m'),null);
selbox.add(new Option('KiloMeters','Km'),null);
selbox.add(new Option('Feet','f'),null);
selbox.add(new Option('Yards','y'),null);
selbox.add(new Option('Miles','mi'),null);
}
}
if (chosen == "2") {
try{
selbox.add(new Option('Square Milimeters','mm2'));
selbox.add(new Option('Square Meters','m2'));
selbox.add(new Option('Square KiloMeters','km2'));
selbox.add(new Option('Square Inches','in2'));
selbox.add(new Option('Square Feet','f2'));
selbox.add(new Option('Square Yard','y2'));
selbox.add(new Option('Acre','a'));
selbox.add(new Option('Hectare','h'));
selbox.add(new Option('Square Miles','mi2'));
}
catch(err)
{
selbox.add(new Option('Square Milimeters','mm2'),null);
selbox.add(new Option('Square Meters','m2'),null);
selbox.add(new Option('Square KiloMeters','km2'),null);
selbox.add(new Option('Square Inches','in2'),null);
selbox.add(new Option('Square Feet','f2'),null);
selbox.add(new Option('Square Yard','y2'),null);
selbox.add(new Option('Acre','a'),null);
selbox.add(new Option('Hectare','h'),null);
selbox.add(new Option('Square Miles','mi2'),null);
}
}
if (chosen == "3") {
try{
selbox.add(new Option('Fluid Ounces','fo'));
selbox.add(new Option('MiliLitres','ml'));
selbox.add(new Option('Litres','l'));
selbox.add(new Option('Gallons','g'));
selbox.add(new Option('Cubic Meters','cm'));
selbox.add(new Option('Cubic Feet','cf'));
selbox.add(new Option('Cubic yards','cy'));
}
catch(err)
{
selbox.add(new Option('Fluid Ounces','fo'),null);
selbox.add(new Option('MiliLitres','ml'),null);
selbox.add(new Option('Litres','l'),null);
selbox.add(new Option('Gallons','g'),null);
selbox.add(new Option('Cubic Meters','cm'),null);
selbox.add(new Option('Cubic Feet','cf'),null);
selbox.add(new Option('Cubic yards','cy'),null);
}
}
if (chosen == "4") {
try{
selbox.add(new Option('grams','g'));
selbox.add(new Option('Kilograms','kg'));
selbox.add(new Option('Ounces','o'));
selbox.add(new Option('Pounds','p'));
selbox.add(new Option('Short Tons','st'));
selbox.add(new Option('Metric ton - Mega ton','mt'));
}
catch(err)
{
selbox.add(new Option('grams','g'),null);
selbox.add(new Option('Kilograms','kg'),null);
selbox.add(new Option('Ounces','o'),null); ...

saad749 commented: Very Helpful and To The Point Answers. +1

Try this..check whether it works for you..

[CODE]
<script>
function setOptions(chosen)
{
var selbox = document.form1.Iunit;
selbox.options.length = 0;

if (chosen == " ") {
selbox.options[selbox.options.length] = new Option('Please select one of the options above first',' ');

}

if (chosen == "1") {
selbox.options[selbox.options.length] = new Option('Milimeters','mm');
selbox.options[selbox.options.length] = new Option('Meters','m');
selbox.options[selbox.options.length] = new Option('KiloMeters','Km');
selbox.options[selbox.options.length] = new Option('Feet','f');
selbox.options[selbox.options.length] = new Option('Yards','y');
selbox.options[selbox.options.length] = new Option('Miles','mi');
}
if (chosen == "2") {
selbox.options[selbox.options.length] = new Option('Square Milimeters','mm2');
selbox.options[selbox.options.length] = new Option('Square Meters','m2');
selbox.options[selbox.options.length] = new Option('Square KiloMeters','km2');
selbox.options[selbox.options.length] = new Option('Square Inches','in2');
selbox.options[selbox.options.length] = new Option('Square Feet','f2');
selbox.options[selbox.options.length] = new Option('Square Yard','y2');
selbox.options[selbox.options.length] = new Option('Acre','a');
selbox.options[selbox.options.length] = new Option('Hectare','h');
selbox.options[selbox.options.length] = new Option('Square Miles','mi2');
}
if (chosen == "3") {
selbox.options[selbox.options.length] = new Option('Fluid Ounces','fo');
selbox.options[selbox.options.length] = new Option('MiliLitres','ml');
selbox.options[selbox.options.length] = new Option('Litres','l');
selbox.options[selbox.options.length] = new Option('Gallons','g');
selbox.options[selbox.options.length] = new Option('Cubic Meters','cm');
selbox.options[selbox.options.length] = new Option('Cubic Feet','cf');
selbox.options[selbox.options.length] = new Option('Cubic yards','cy');
}
if (chosen == "4") {
selbox.options[selbox.options.length] = new Option('grams','g');
selbox.options[selbox.options.length] = new Option('Kilograms','kg');
selbox.options[selbox.options.length] = new Option('Ounces','o');
selbox.options[selbox.options.length] = new Option('Pounds','p');
selbox.options[selbox.options.length] = new Option('Short Tons','st');
selbox.options[selbox.options.length] = new Option('Metric ton - Mega ton','mt');
}
if (chosen == "5") {
selbox.options[selbox.options.length] = new Option('Fahrenheit','df');
selbox.options[selbox.options.length] = new Option('Celsius','dc');
selbox.options[selbox.options.length] = new Option('Kelvin','dk');
}

}
</script>

<body>
<form id="form1" name="form1" method="post" action="">
<p>Which entity will you like to convert:
<select name="entity" id="entity" onchange="setOptions(document.form1.entity.options[document.form1.entity.selectedIndex].value);">
<option value="1" selected="selected">Length</option>
<option value="2">Area</option>
<option value="3">Volume</option>
<option value="4">Mass</option>
<option value="5">Temprature</option>
</select>
</p>
<p>
<input name="Iamount" type="text" id="Iamount" value="1" size="15" />
<select name="Iunit" ...