Hopefully there's no need to explain KeePass, an absolutely brilliant password manager that holds steady at the top of this category of applications for years. It is a great group of applications for multiple platforms that all support reading and writing the encrypted password storage file.
KeePass features a plugin architecture, allowing other developers to extend the functionality through their own modules.
Here are some of my favourites:
- KeePassHttp - fantastic link between browsers and KeePass. Note that separate browser extensions are needed to read entries through KeePassHttp. This is just a KeePass extension to listen for requests.
- KeeAgent (link) - SSH key provider. Emulates pageant.