I was researching some ready built charting libraries for displaying charts in PHP.
Following are the ones I found interesting and good ones to try..
http://quimby.gnus.org/circus/chart/chart-manual.php – This one is a very lightweight charting library which creates image charts.
http://www.maani.us/charts/index.php?menu=Download – With this one you can display dynamic charts in flash (requires flash player at client system)
http://www.aditus.nu/jpgraph/ – This is another charting library with lot of features with support for PHP4 and PHP5. Its not so light as the download size is about 4.5 MB (Yet to try this one due to this reason)
If you know/have used any other good PHP charting libraries, please shout here !!