What's Sysmon ?
Sysmon is a tool to monitorise the state of one or more computers. It's based on a daemon and a php script.
The first has to be runned in all boxes you need to check, the second calls the daemon and prints the state into a nice web frontend.
The sysmond functions can be easily expanded by writing modules.
You can read the man page here.
Documentation to write modules here.
Screenshot and samples