Ajax is the hottest technology trend for web developers and it is standards based so it works with both Internet Explorer and FireFox
Ajax combines 3 already hot technologies: CSS, XML, and JavaScript and gives professional web developers the ability to create more sophisticated and responsive user interfaces (like Flash) but without requiring proprietary development tools or browser add-ins
Some of the topics covered include:
Ajax communication methods
Ajax Patterns
Using XML information natively and through the use of JavaScript
Building a web based Ajax RSS reader
Web services including calling web services from JavaScript
JavaScript Object Notation (JSON)
Ajax Web site "widget" examples using Web services, JSON, PHP, .Net, and RSS including news, weather, RSS, web search, and web mail