As for what you must do to handle the services at the server side, that's entirely up to your choice of Web application language and choice of database, among other things. Use what you know best, or take the time to learn other Web application languages you suspect will ease the burden of writing server-side code.
Finally, keep an eye on what you manage at the server side and what you manage at the client side. Depending on what your Ajax Web application does, you may find some performance gains by storing certain information in cookies, or you may speed up performance by storing the information at the server side. Use common sense and experiment between the two approaches to see which performs best.
It's not always easy to build a killer Ajax application, but hopefully this tutorial on the simplicity of how Ajax works will encourage you to give it a try. Now grab a toolkit and go!
Nicholas Petreley is Editor in Chief of Linux Journal and a former programmer, teacher, analyst and consultant who has been working with and writing about Linux for more than ten years.