At first what does Ajax mean?
AJAX (Asynchronous JavaScript and XML), is a web development technique used for creating interactive web applications. Ajax is asynchronous, in so far as extra data is requested from the server and loaded in the background. This is intended to increase the web page’s interactivity, speed, functionality and usability. Ajax function calls are usually made in Javascript using the XMLHttpRequest object. The asynchronous content doesn’t need to be formatted in XML.
Scripts for your Website
As quite every modern website makes use of at least a bit of Ajax you may want to have a few of those cool effects for your page. So I collected the best scripts for you. All of them are free to use and easy to install.
Lightbox 2 - Lightbox is a simple, unobtrusive script used to overlay images on the current page. It’s a snap to setup and works on all modern browsers.

Thickbox 3.1 - ThickBox is a webpage UI dialog widget written in JavaScript on top of the jQuery library. Its function is to show a single image, multiple images, inline content, iframed content, or content served through AJAX in a hybrid modal.
Glider - This script makes it easy to create a sliding carousel component like the one seen at www.panic.com/coda.
TableOrganize - This script basically allows you to re-organize the rows or columns and browse the table using the up/down arrows.

Clickheat - ClickHeat is a visual heatmap of clicks on a HTML page, showing hot and cold click zones.

Reflection.js - allows you to add reflections to images on your webpages. It uses unobtrusive javascript to keep your code clean.
AjaxIM - ajax im (”asynchronous javascript and xml instant messenger”) is a browser-based instant messaging client. It uses AJAX to create a near real-time IM environment that can be used in conjunction with community, intranet, and social websites.
Relay - An Ajax directory manager that works and looks like the familiar one of windows and mac systems.
SWFUpload - is a small JavaScript/Flash library to get the best of both worlds. It features the great upload capabilities of Flash and the accessibility and ease of HTML/CSS.

NicEdit -NicEdit is a Lightweight, Cross Platform, Inline Content Editor to allow easy editing of web site content on the fly in the browser.
Vuzit - Vuzit is a web based document viewer you can embed in any web page. It’s fast and it’s free!
flot - Flot is a pure Javascript plotting library for jQuery. It produces graphical plots of arbitrary datasets on-the-fly client-side. The focus is on simple usage (all settings are optional), attractive looks and interactive features like zooming.

Control.Tabs - creates a tabbed interface from an unordered list of links/anchors that point to any elements on your page that have an id attribute.
IE7 - is a JavaScript library to make MSIE behave like a standards-compliant browser. It fixes many CSS issues and makes transparent PNG work correctly under IE5 and IE6.
Resources for more scripts
Scripteka an extensive library of Prototype and Script.aculo.us based extensions/plugins.
At AjaxDaddy you can see Ajax examples, javascript scripts and web 2.0 demos in action.
MiniAjax, a showroom of nice looking simple downloadable DHTML and AJAX scripts.
And have a look at more than 1000 Ajax examples at AjaxRain.com






