The symon project consists of three parts; a data monitor, a data consolidator
and a data displayer. 

symon is a is a lightweight system monitor that measures cpu, memory, pf,
interface and disk statistics every 5 seconds. It sends this data on to symux
for further processing. symon has been designed to inflict minimal performance
and security impact -- it can be run as nobody on the system it monitors. 

symux is a non-privileged daemon that listens to incoming symon traffic. symux
can write the incoming symon streams into rrd files. Clients interested in
monitoring machine state can also log into symux and receive data as ascii as
it arrives. 

WWW: http://www.xs4all.nl/~wpd/symon/