On the php|architect site today there's a new tutorial from Joshua Thijssen about using RDD graphs in PHP. RDD graphs are commonly used in dashboard monitoring applications for everything from web servers to network traffic. Joshua introduces you to the topic and shows you how to use the extension in a sample script.
You may not be familiar with the term RRD graph, but if I show you one, you probably recognize them instantaneously. They are used to plot all kind of data against time in a very easy way which is why they are used a lot in all kind of applications. Even though many consider RRD as a library to create graphs, it is actually more than that: it's a complete system to store aggregated data in a very efficient way.
He talks about how to load in the extension (or the command line, if it won't compile) and create a sample graph or two from some database information. The functions the extension enables make it simple to create some basic graphs quickly and easily.