Windows calculator progam embedded in a screenshot of itself, 2012
Here the program calc.exe, the most popular digital calculator used worldwide, is steganographically embedded in a screenshot of itself. The image of the program contains the program.
Clicking on the below screenshot will give you the (enlarged) 4096x4096 pixel image in which the program calc.exe is embedded:

It is embedded using the encryption algorithm Rijndael, with a key size of 128 bits. You can use the steganography program steghide on a Linux or Windows system to extract calc.exe from the image of itself.
Below I use steghide on a Debian GNU/Linux system to encode the file:
julian@x200:~/tmp/system_apps$ du -h calc.jpeg
2.7M calc.jpeg
julian@x200:~/tmp/system_apps$ steghide embed -ef calc.exe -cf calc.jpeg
Enter passphrase:
Re-Enter passphrase:
embedding "calc.exe" in "calc.jpeg"... done
The passphrase I typed is a quote from Pythagoras (572-497 B.C.E). You will need this passphrase to extract calc.exe from the image:
"Number was the substance of all things."