Nagios - Network Availability Monitor
Seems that Netsaint has changed names and hands. the new version of NetSaint is called, you guessed it, Nagios. Improved interface, improved report capability. It's a nice, free, lil' package that lets you monitor not only devices but services too. Get availability reports, schedule downtime, etc. etc. Easy to setup, MUCH easier to configure than previous versions. I use it, check it out.
Did I mention it's free? www.nagios.org
Overview from the site
Nagios is a host and service monitor designed to inform you of network problems before your clients, end-users or managers do. It has been designed to run under the Linux operating system, but works fine under most *NIX variants as well. The monitoring daemon runs intermittent checks on hosts and services you specify using external "plugins" which return status information to Nagios. When problems are encountered, the daemon can send notifications out to administrative contacts in a variety of different ways (email, instant message, SMS, etc.). Current status information, historical logs, and reports can all be accessed via a web browser.