Seeking recs for Debian server monitoring

[usernamenumber]

Hey sysadminy types, I have a colleague who has developed a pretty cool-looking system for making cheap phone calls online, paid for with bitcoins (http://chiliphone.com/main/content/about). What it needs now is some kind of monitoring solution because, as he puts it, "I find myself worrying about 'uuh... is it up? does it have too much load? are there any errors?' things like that...".

If I was still working at Red Hat (and he wasn't running Debian), I would be able to tell him about our many excellent commercial offerings for such things, but I'm a bit out of practice on free/cheap, Debian-friendly solutions. Last I checked, Nagios was the go-to for that kind of thing. Does anyone else have other recommendations?

Comments

[laurion]

Munin is good. I've used that in the past. I've also used pingdom for basic up/down checks. Heard good things about Monit and Cacti as well.