Google Maps is an online mapping tool that is without a doubt one of the coolest online resources I've ever used. Online map services aren't really new but Google Maps is so unique in its map interface that it is truly a groundbreaking application.

Learn how to create simple XML-RPC/SOAP web services using PHP and SOAP.

Learn how to create those XML files for podcasting your audio files out to the world.

One problem being addressed with XML is not very hard at all, and is actually quite fun. I'm referring to Apple's iTunes digital music service, which you probably didn't realize had anything to do with XML.

This tutorial explores a feature of Google's search engine called Google Sitemaps, which allows Web developers to automatically notify Google of changes in web page content so that Google can know that the pages exist, as well as indexing the pages more frequently. Of course, Google Sitemaps uses XML or I wouldn't be bothering to tell you about it. It represents a clever and efficient use of XML that serves as an important tool in any Web developer's toolkit.

How to use XML to mine data on the web, how to use it to interact with existing data services such as iTunes and Google, and how to use it in applications such as e-books, online speech synthesis, and multimedia.

RSS is XML-based technology, which simply means that the language used to code news feeds is an XML markup language. There are a variety of different ways that you can use RSS. You can display RSS feeds from other web sites on your web site, you can build your own library of RSS feeds and view them regularly using special software called a news aggregator, or you can syndicate your own site using RSS so that other people can view your feeds. This tutorial touches on all of these uses of RSS.

An important variant of XHTML is called XHTML Mobile, and its focus is on mobile devices that don't require the full XHTML feature set. You've probably experienced the challenge of trying to 'browse' the web on a mobile phone. If so, you probably understand how constrained the mobile phone environment can be in terms of limited screen space, processing power, memory, and so on.