In case you don't already know Pixel Bender is the newest thing from Adobe for runtime image processing. The great thing about it is that it runs on the GPU, thus performing faster and leaving the CPU for other stuff.
I've never been a math fan, so my examples are very basic, just a grayscale filter and an overlay. I got some inspiration from Miti's examples.
Once I got to know how the filter works I wanted to go a step forward. So I also created an Effect (a tween of the filter), I used the SDK BlurFilter as an example. The advantage of having this Effect is that you can stop/pause it, set properties like duration, easing, targets and all the other stuff that the framework effects support. Further more the filters run on the GPU, so it is faster.
You can download the project here.
PS The applications target Flash Player 10.