Note for users of old versions: before 1.0.0, this project was known as "Secret Agent". I changed the name because there is another security-related application with the same moniker. I'm sorry for any inconveniences.
Quintuple Agent stores your secrets in a secure manner.
Its main use at the moment is with GnuPG (an e-mail encryption/signation solution compatible to OpenPGP), or PGP 2.6. You can store your passphrase with Quintuple Agent, and have it provide that passphrase to GnuPG or PGP everytime it is needed. In this way, you'll only have to enter the passphrase once per session, every hour, as you like it - but not every time you want to sign an e-mail.
If you're more the visual type, you may want to check out the gratuitous screenshot section.
Quintuple Agent is free software under the GNU General Public License. The latest stable release is 1.0.3, and can be downloaded from here. You may want to download & check the package's signature, too. Users of Debian unstable should already have the package available from their nearest mirror. You can also generate your own Debian package (e.g. for potato) from the tarball above.
If you want to know more, you can read the manual, or check out the user-visible changes.
Please direct comments on this page or on Quintuple Agent to
robbe+qa@orcus.priv.at