Good-bye, Nagios.
I hate configuring Nagios. I thought I would get used to it, but I just can't. (I must admit that Nagios is an improvement over Big Brother, which is what we used to use at work.)
I don't know how I missed it for so long, but I just stumbled on mon. mon is easy to configure, well thought out, modular, and just plain better than Nagios, IMHO. In a couple of hours time I had mon doing more than I had been able to muster the gumption to configure nagios to do in the past 2 months. That's perhaps the biggest benefit of mon over Nagios: mon is fun, Nagios is a chore.