Ncrypt is a free & open source tool for data encryption, written in C#. It supports AES, Rijndael, TripleDES, DES and RSA. More implementations will follow soon. Hashing is also implemented, it supports MD5, RIPEMD-160, and SHA-1 to SHA-512.
Ncrypt will also have an command line implementation, which will follow soon.
Check here for the latest releases. Pre-releases are not recommended for excessive usage, they might contain bugs or errors.