And what about lossless image formats like .tiff or .bmp? These allow you to basically store any data in an image, and although the photo looks just like noise

And what about lossless image formats like .tiff or .bmp? These allow you to basically store any data in an image, and although the photo looks just like noise it's a completely valid image file with minimal overhead. I do know some people that use that for backups on picasa and flickr, which have unlimited storage and 1TB respectively.