Auto-resize textbox

Facebook like textboxes

Download this jquery plugin
http://james.padolsey.com/demos/plugins/jQuery/autoresize.jquery.js

Then apply this for your textbox

$('textarea#comment').autoResize({
    // On resize:
    onResize : function() {
        $(this).css({opacity:0.8});
    },
    // After resize:
    animateCallback : function() {
        $(this).css({opacity:1});
    },
    // Quite slow animation:
    animateDuration : 300,
    // More extra space:
    extraSpace : 40
});