I was about to write a script using OpenSSL to monitor the SSL certificate expiration dates for a few servers when it dawned on me that someone had probably done this already.
The ssl-cert-check shell script takes a list of hosts/ports and prints out the expiration date (and how many days away that date is). It can also be configured to email a message for any certificates expiring in less than N days for easy cronibility (?). Seems lovely!
Evan Hoffman's Blog 