Sapphire has released a plug-in for Photoshop 6. Shapes Volume 6 is a custom shape program that is supported by Mac OS 8.5 and higher, but not OS X. According to Sapphire:
400 new intense custom shapes for Photoshop 6 - super intense zigzag/dynamic shapes - great for web design and layer effects; can be distorted, twisted, effects applied, liquified and more. PC and Mac Demos available.
You can find more information for this product at the companyis Web site. Shapes Volume 6 is available for US$25.19.