For a few projects, I've been looking around on how to do some photoshop style effects and remembered Silverlight and WPF have shaders!
My hunt both started and ended with Nokola's Silverlight tool Easy Painter.
- Pastel, Old Photo (LOMO effect), and pencil sketch
- Light Saturation (his old blogs.msdn.com has a write up on it)
- Water Ripples
And then you have the community's effects
- Rene Schulte's old movie effect
- A ton on CodePlex as well