Secret Layer
From Just Solve the File Format Problem
Secret Layer by EasySector Software (Dimitry Chakogrenko) is a Win32 program that hides multiple files and text in a JPG, GIF (including animated), BMP, or PNG
The Pro version adds the ability to span multiple carrier files and password protection with AES, Blowfish, Cast, DES, IDEA, RC5 or Twofish
v2.7.1 is not compatible with v2.8.1