My application is in PHP.
I have a payment form where shipping is being calculated through AJAX when the user clicks on "Calculate Shipping" Button. The trouble is sometimes there is a time delay before the Servers Send back the info to the Browser.
Meanwhile I'd like to display a "Processing.. Please wait" notification to the User.
From my research it appears like Yahoo's YUI library is one of the best. They have something called a 'Panel' which allows you to easily define options, of how it looks like. The panel has 'show' and 'hide' methods, so all you need to do is call the 'show' right before and ajax call, then the 'hide' once you get the response. Inside the panel, you can have text, html, images, whatever you want.