Since I got some positive reenforcement for my posting on Nagios I’ll go ahead and point to this posting on screen; which I use as well. I use screen on headless servers, a lot.
Screen is much lighter than what I used to do. I’d run an X server on the headless machines with an in memory virtual display device. On that server I’d run a XEmacs to which I would typically connect using gnuclient. Occationally I’d connect to the X server using VNC. The nice thing about this approach is you can run a rich visual display of the server’s status in the memory resident X server and pop it up on demand.
HA! I see that Justin Mason has some screen tricks as well.