Graphing With PHP and GD

As more and more web sites start incorporating a database in some part of their design, we can start using the data that those databases collect to display statistics. A lot of web sites today have opinion polls or voting applications somewhere. It's one thing to display the data in a table, but quite another to create a graph from the data. Sure, we could slap together a workable bar graph with some tables, but what about line graphs or pie graphs ? PHP has a set of Image functions that will allow us to create images on the fly - let's see how these functions can be put to good use and create some graphs.