A new tutorial has been posted over on the Codewalkers.com website today looking at creating a "first mashup" - a Flickr Puzzle (by Timothy Boronczyk).
I'll take you through a sample project in this tutorial—a mini-mashup if you will—that will take a photograph, break it up and present it to the user as simple puzzle.
They use a picture from Flickr, the drag & drop feature of the Yahoo UI Library, and some PHP 5 (including GD) to create a simple, fun little application. It shows how to integrate content from one location, use functionality from another, and combine them into one seamless application.