Multiple Eyepairs Only is a project to define a file format and to provide tools to use cryptography for things like four-eyes principles. The key idea is this: if information should only be accessible to a group of people together, with the additional possibility to have some redundancy in participants, then MEO is for you.
jEncrypt is a commandline file encryption archiver. Files are encrypted with the AES-CTR mode, which was recommended by the National Institute of Standards and Technology in 2001 (NIST SP 800-38A). AES-CTR mode only provides confidentiality. It requires a message authentication code such as CBC-MAC to ensure an encrypted message is not accidentally modified or maliciously tampered with, which jEncrypt currently does not provide.
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.
Bitcoinproof creates a forgery-proof timestamp for your data, secured by the Bitcoin network. It allows you to prove that a certain event happened before a certain point in time. Maybe you want to prove that the damage in your flat already existed when you moved in, or that you were in possession of a great artwork before it was published, proving you are the author.
Shasplit takes a large data block, splits it into smaller parts, and puts those parts into an SHA-based content-addressed store. Reassembling those parts is a trivial "cat" invocation. Repeating parts (e.g., from previous split operations) are stored only once, which allows efficient incremental backups of whole LVM snapshots via Rsync. Shasplit shows its strengths on encrypted block devices, but might be useful for non-encrypted data, too.
libbadger is an alternative to existing decentralized authentication systems which require regular direct communication between client and authority. Badger allows clients to authenticate with servers easily and securely in a browserless environment because there is no necessity to tunnel the client to an authority for the purposes of its own authentication. Using Badger, clients only need to communicate with an authority once in their lifetimes.