I use Nagios and NRPE to monitor my servers. With this you can check any number of things, including the db connections, slow queries, radius, cpu time, memory, any number of ports, etc... Provides a web interface and full reporting, including notifications by email, text message... It works beautifully.
Regards, Andrew - List info/subscribe/unsubscribe? See http://www.freeradius.org/list/users.html
