-Expensive shell account for IRC access. Yay screen/irssi!
-Hosting four domains and varying subdomains
-E-mail for all of the above (+ webmail over SSL)
-MySQL database... but who doesn't? The difference with mine is that the root user is allowed access from anywhere, without a password... but it requires an X509 cert. Good times.
-My linode actually contains the raw files for my Certificate Authority... backed up, of course.
-OpenVPN access (on :53/udp, yay for walking around firewalls)
-IPSEC access
-DNS master for my domains, with key authentication allowing me to update my DNS from anywhere, securely
-File hosting
-Kerberos realm
-LDAP (coming soon!)
-PGP/GPG key backup
I like my crypto

Do you know of any good guides for setting up OpenVPN and IPSEC? I tried a while back and wasn't able to get things properly working - one of the issues was my firewall configuration, though I know there were others.