What software do you use to monitor your servers and the services running on them? I'm looking for Nagios competitors that are better and easier to set up. Right now, I've got a few Perl scripts that send emails if the disk gets full or if my site isn't returning the expected content, but it's not ideal.
Zabbix was also pretty simple to set up and it comes with a bunch of monitoring tool out of the box if you have the client agent. My last job was considering it instead of trying to update and practically re-write our Nagios configs that were dragged from v1 to v2 and incompatible with v3.
If I recall correctly, Zerigo's (<a href="http://zerigo.com" rel="nofollow">http://zerigo.com</a>) Watchdog service has a free tier.<p>I've used their monitoring and DNS hosting for a while, and have been thrilled with everything; performance, service, control panel.