Enfomi is a cross-platform standalone password-based encryption/decryption program that supports 27 algorithm variants (including AES 256bit). Archives can be self-decrypting, thus making it perfect for mobile applications.
Cryptomni is a program which can encrypt and decrypt files using the one-time pad cipher. If a key is truly random, kept secret, and never reused, this encryption algorithm can be proven to be unbreakable.