I also found a piece of software a few years ago that let you encrypt a file inside a Jpg image, but the onlyway to retrieve the file was to know that there was a file in the image in the 1st place and sum1 else could then get the file from the image if they knew the password.
Not really affecting u with a virus, but it enables ppl to share files or even viruses without any1 else knowing about it. If any1 knows the name of the software that does this, i'd like to know again as this could be implemented quite usefully, thanks !