Every now and then I search for filters and plug-ins for imaging programs
Here's a list of some free one I found. ( all are Photoshop type Plug-in filters )
These links take you right to the down load. Most have read me files describing the filters and installation instructions.

If anybody else no of any free ones please post ( I always looking for new ones )

Grids ( creates grids )
http://www.boxtopsoft.com/plugpage/download/Windows/grids.zip

Harmonics ( creates a wave line )
http://www.boxtopsoft.com/plugpage/download/Windows/hmx107d.exe

Evaluate ( color processing, blurs, grains many functions )
http://www.boxtopsoft.com/plugpage/download/Windows/evaluate.zip

Camo 101 ( generates camouflage textures )
http://www.boxtopsoft.com/plugpage/download/Windows/camo101.exe

Night Vision ( generates some real interesting effects )
http://www.boxtopsoft.com/plugpage/download/Windows/nv102.exe

Border Mania ( create different type borders around the image or selection )
http://www.boxtopsoft.com/plugpage/download/Windows/nvrbp39.exe

Grain Generator ( creates grain noise )
http://www.boxtopsoft.com/plugpage/download/Windows/graingen.zip

Halftone ( generates halftone patterns )
http://www.boxtopsoft.com/plugpage/download/Windows/halftone.zip

Color Bars ( create color bar templates for computer and television monitor calibration )
http://www.boxtopsoft.com/plugpage/download/Windows/colorbars.zip

3D Spheres ( generates 3D spheres )
http://www.boxtopsoft.com/plugpage/download/Windows/3dsphere.zip

Ripleyer ( adds scan lines )
http://www.boxtopsoft.com/plugpage/download/Windows/ripleyer.zip

Scrible Filters ( 10 filters : 4 Way Mirror, Color Spin, Color Split, Doughnutz, H Metal, Solarizer, Noisey, RGB Gradation, Super Emboss )
http://www.boxtopsoft.com/plugpage/download/Windows/Scribe_Filters.zip

Sabercat ( a set of 14 filters plaid generator, colorizer, hardlight pixelise, magic mirror, modula painter, dead ceneter mitoisis and more ) some of these have crashed PS for me, but not every time there used.
http://www.boxtopsoft.com/plugpage/download/Windows/Sabercat.zip

CrescentMoon (a set of 8 filters that include; color spinner, color switcher, cut glass, terracotta, tri mirror tile, strip tile, fade out, spooky fade and others )
http://www.boxtopsoft.com/plugpage/download/Windows/CrescentMoon.zip

Berthold Daum Filters ( corrective filters : radial gradient and unfringe )
http://www.boxtopsoft.com/plugpage/download/Windows/Berthold_Daum_filters.zip

Ecrossc ( 3 filters Falsecolor3 is a palette mapper, Flutter is a ripple filter, and Lead Embossa directional embosser )
http://www.boxtopsoft.com/plugpage/download/Windows/Ecossc.zip

Cloud 2.2 ( makes seamless cloud )
http://www.boxtopsoft.com/plugpage/download/Windows/mmCloud22.zip

Gothic ( noise type filter )
http://www.graphicxtras.com/demos/gothicfreebie.zip

Andrew'a Filters ( 5 filters, noise, color and fractal type filters )
http://www.graphicxtras.com/demos/filters_1.zip

Kangaroo, ( 71 Plug-Ins, most are fractal type filters )
http://www.photoshop-filters.com/downloads/kang/pc-kang.zip

Stephen Ray