JSON – Elegant Approach for cross domain AJAX scripting:

Tried it and fell in love with it right away. This is a sure winner for those writing cross domain widgets for the Internet. JSON is a data format that can be handled with ease in JavaScript (or Java or any programming/scripting language). It also allows cross domain scripting which is not supported by AJAX. Here are some cool resources to get started.

Introduction to JSON:

Using JSON to exchange data: