This is a nice DOS-based encryption program. This uses 128-bit encryption to encrypt any file into a secure file. You can choose your own encryption key, so even if someone has Fast Encrypt, they can't decode your file unless they have your encryption key. For best results, encode only .ZIP files and, when encoding a file, be sure to remember the key or let it save the key to disk.
WARNING: File size limit is around 6MB. Anything after that is truncated.