Input Limiter jQuery plugin will allow you to limit input into form fields. It can
display a message as the user types to let them know how many
characters they have remaining.

Use:
Step 1: Add javascripts references into your page
<script type="text/javascript" src="jquery-1.3.2.min.js"></script> <script type="text/javascript" src="jquery.inputlimiter.1.1.js"></script>
Step 2: Add textbox or textarea
<input type="text" id="text3" size="30" /> <textarea rows="3" cols="30" id="textarea1"/>
Step 3: Apply input limit to input element
$(function() {
$('textarea').inputlimiter({limit: 100});
});
Input Limiter also provides various options like remText to customizing remaining text message, limitTextShow which Determines whether the limitText will be displayed after the remText etc.
References:
WebSite: http://rustyjeans.com/jquery-plugins/input-limiter
Demo: http://rustyjeans.com/jquery-inputlimiter/demo.htm
Download: Download Now
Not working on jquery-1.4.2 version.