rfc3394 is a C# implementation of the RFC 3394 key-wrapping algorithm. The associated assembly provides two simple operations: one to wrap key data, and another to unwrap the key data. This code also includes a fairly comprehensive unit test library which, among other things, ensures that the implementation is verified against the test vectors provided in RFC 3394.
CryptSharp provides a number of password crypt algorithms: BCrypt, MD5 (and Apache's htpasswd variant), PHPass (WordPress, phpBB, Drupal), SHA256, SHA512, and Traditional and Extended DES. It also includes Blowfish, SCrypt, and PBKDF2 for any HMAC (.NET's built-in PBKDF2 implementation supports only SHA-1). If you are looking to store passwords, odds are CryptSharp will have the algorithm you want.