decayscreen - decay image, based on XScreenSaver hack with the same name
drawing_generative - draw image using strokes based on channel value
drawing_strokes - draw image using lines (aka robot drawing)
fractalify - draw mandelbrot/julia fractals using channel data from image
imagelens - use image channel data to displace pixels. You can use different image as lens and to process.
mirrorimage - mirror parts of the image to other parts, 24 modes for rectangular (12 for squared) images
ntsc_analogtv - xanalogtv XScreenSaver hack ported to processing
slitscan - simulate errors during scanning (more digital way)
wzipprocess2 - recompress image using wzip method (Haar wavelet transformation)
imageslicer - few algorithms based on segmentation of the image
cutsort - cut image to lines of random length, sort (or not) and encode image, decode to get glitched result
distorter - another way to pixel displacement
lz77 - two script to compress/decompress image/binary with random glitch compressed data
median_filter - median filter with option to choose other points (not only median)
wrongqsort - cut image to lines/parts and use buggy QuickSort to sort pixels
wavelets - wavelet compression tool
pngglitch - corrupt PNG files (using hacked decoder)
ultimateSort - partly sort thresholded pixels with various algorithms
moire - random moire patterns generator / simulator
pix2line - convert pixels into lines snapped to noise grid
pixeldrifter - drift pixels using channel data
watmap - divide target image into regions and map with most matching part from source set
blendimages - blend source image set into target
threadraw - draw vertical threads based on image (similar to generative draw)
decompose_paint - decompose image into sqares/rectangles and fill it with some pattern
imsyntex - reconstruct image using texture synthesis algorithm
fm - frequency modulation and demodulation
composite_video_simulator - very precise VHS/Composite Video/Tape simulation, based on: https://github.com/joncampbell123/composite-video-simulator
Obj2Raw - convert OBJ vertex data to RAW 8 bit signed (for sonification purposes)
granularresynth - Granular (re)synthesis of any RAW using other RAWs for visual/audio
-> sonification - image sonification
-> GLIC - glitch image codec
TEMPLATE - clean template sketch with some predefined functions

Processing 3

In order to have scripts working in Processing 3 change (thanks to Aitor):

size() to surface.setSize()
sketchPath to sketchPath()
buffer.loadPixels() must be called after buffer.beginDraw()
Calling a function that draws from the buffer into the window needs to be done in draw()

Some of them are ported by:

https://github.com/wabisabit:

blendimages
decayscreen
Obj2Raw
pixeldrifter
pngglitch
slitscan

https://github.com/philhudson91:

threadraw
ultimateSort
watmap
wavelets
wrongqsort
wzipprocess2

Pull request welcome!!!