Cybia offers a nice collection of free Photoshop plugins. These plugins are divided in two series, the “Works plugins” which includes 8 different plugins, those are
AlphaWorks : 6 filters with various transparency properties
ColourWorks : 20 filters for modifying the colours in your images
EdgeWorks : 20 filters for producing edge/contour effects
ScreenWorks : 30 filters with different screen/mesh overlays
EmbossWorks : 20 filters containing simple emboss variations
SwapShop : 15 filters that “swap” colour values in your images
MasterBlaster : 20 filters to “blast” colours giving a strong cast
Mezzy : 15 filters for producing mezzo and grain effects
These plugins were created sometime ago but they are still useful. The one I use the most out of these is the Alphaworks.
The second series is called “Fotomatic Plugins”. This series includes 8 plugins that offer effects based on traditional photography techniques. The Fotomatic plugins includes the following plugins.
You can check them out at Cybia’s site