Filter Forge is designed to help you create stunning filters as a high-end plug-in for Adobe Photoshop. It allows you to build your own filters, textures, visual effects, distortions, patterns, backgrounds, and frames in a few clicks. The key features of Filter Forge include a visual filter editor and a free online library of 6000+ user-created filters to which anyone can contribute. If you're a dab hand with Photoshop then creating filters is something you'll be familiar with but if you're not, you might need a helping hand which is what Filter Forge aims to do. Filter Forge's interface is simple enough to use even for beginners. You can use it either within Photoshop or as a standalone plugin.
What makes Filter Forge stand out from most average plugins are three main features. The obvious one is that via the simple editor, you can create your own filters. Although it is quite straightforward with an excellent user guide, Filter Forge still requires some knowledge of creating filters to be used effectively. Note that all filters support 16- and 32-bit modes only in Photoshop.
Additionally, Filter Forge is very much a user oriented application. There are thousands of free filters created by other users and if you become a contributor yourself, you receive the full version of Filter Forge absolutely free. It's not clear how good your filters have to be to qualify but it seems like generally anything goes.
Filter Forge is an excellent filter creation tool with a strong community spirit that will enhance your Photoshop creations.