cpm (Console Password Manager) is a small console tool to manage passwords and other sensitive data and store them in a public-key encrypted file. It also allows you to configure the whole hierarchy yourself, so it's easily adoptable for many requirements. The encryption is handled through GnuPG, and the data inside is stored as XML.
Universal Password Manager (UPM) allows you to store usernames, passwords, URLs, etc. in an encrypted database protected by one master password. Its three strongest features are simplicity (it provides a small number of very strong features with no clutter), the ability to run cross-platform, and database sharing. Rather than having many separate databases (home, work, etc.), database sharing allows you store your database at a remote location (password protected HTTP URL, for example) and then have UPM automatically keep your local database in sync with the remote database.
mdp stands for "Mot de Passe", which means "password" in French. It wraps GnuPG for encryption and deals with all the small details of generating, managing, and fetching your passwords. It is similar to many other programs, but differentiates itself with simplicity (not button-driven simplicity, but with a Unix less-is-more style). For example, beyond the use of GnuPG for encryption, it lets you use your own editor to manage your passwords, categorize them, and delete them. In order to avoid passwords lingering on your screen, the results from the queries are displayed through a custom pager which is cleared after a customizable timeout (defaulting to ten seconds).