PHP graphics on-the-fly

A nice HOWTO on Creating graphics on the fly using PHP

PHP has the amazing ability to create dynamic images on the fly using server-side scripts. The basis for this functionality is the GD Library, an ANSI C library designed by Thomas Boutell. The library supports most popular image file formats except for .GIF files (although the author promises to add.GIF support once the LZW patent expires on July 7, 2004).

The GD Library is integrated in PHP versions 4.3 and above. If you are using an older version of PHP, you will have to install the graphics support manually. Plenty of information is available on setup.

Also, JpGraph is an excellent and free PHP Graph Creating Library available for non-commercial, open-source or educational use.