PngBin
From Just Solve the File Format Problem
PngBin is an open source program that converts any binary data to a PNG image file and vice versa
An image produced by PngBin will have every property like a normal PNG image except that when viewed by an image viewer, It will appear broken and noisy (which is normal for any PngBin images).
Optional AES encryption
It can also convert a whole folder of files into a series of images to facilitate uploading to image sharing sites.
