Playing around with PAM modules lately, I have discovered libpam-ssh and pam-keyring. Both require some mucking about in /etc/pam.d/, but provide some worthwhile benefits. libpam-ssh provides automatic spawning of ssh-agent, and populating ssh keys as required. This is handier than the keychain package as you do not have to enter passwords for each key, or even at all other than the initial login. The downside, of course, is that your ssh key passphrases must be the same as your system password.
