Recommend Linux or browser based Venn diagramming tool

I am looking for a tool to draw a nice Venn diagram to use on a PHP Linux site that already uses Flash to draw a graph ( Open flashcard 2 ). Free (like beer or speech) would be nice, but not necessary.

So, it must be one of the following (in my rough order of preference):

• Browser (Flash)
• PHP library
• Linux command line application
• Web service

So far, the options I know about are as follows:

• Google charts
• Write something yourself using PHP GD or Flash