The Plugin Site Harry's Filters
Harry's Filters 3.0 lets you choose the appropriate effect without hassling through different menus and dialogs. The main effect categories are called Color, Artistic, Gradients, Patterns, Warp, Noise, En/Decrypt, Other and Nature. They include filters for changing the image color or mood, for creating artistic effects, producing colorful gradients or impressive patterns, warping images and adding special noise effects to image. Additionally they let you encrypting and decrypting images with 64 bit keys, produce zoom, mirror or paint effects as well as natural effects like lightning, tornado and polar lights.

REDFIELD PLUGINS Jama 3D
Jama 3D is a freeware Adobe Photoshop compatible plug-in filter. It's a simplest way to create corrugated and cellular like patterns from 2D images. You can easily make some kind of bricks and herring bones textures. Sequenced filtering produces bizarre unreal deformations of original picture, crumpled paper effect etc. Using a different 2D shapes on a transparent layer, get you effects of complicated 3D borders. Edges antialiasing option improves a dithering. The filter is extremely compact and accessible.

Auto FX Software Dreamy Photo
This effect is part of the DreamSuite product line from Auto FX Software. It is available for free but does require a serial number to activate. Enter in your e-mail address in the field below and we will send you a serial number to activate this free plug-in.

Martijn W. van der Lee UnPlugged filters
The UnPlugged filters are a set of free plugins for graphical applications such as PhotoShop, Premiere, Paint Shop Pro and basically every other program capable of using PhotoShop plugins. The total set of nearly 100 filters is divided in four separate archives which sorts them into the categories "Colors", "Effects", "Shapes" and "Tools".

Kerlin Softworks Mosaica
Mosaica was written because the PhotoShop and PaintShopPro implementations of this simple filter are a bit lacking when it comes to creating mosaics for 3D environments. It's similar to mosaic functions you've seen elsewhere but has a few more features that make it pretty nice. For starters, it creates a matching bump map so you can synchronize the image and bump map in your 3D app.