I recently hat a great talk to some of the people who are involved into the Icinga project at CeBIT.
They build an Open Source monitoring software which was forked from Nagios and gained lots of attention in a very short amount of time. The IPFire project has been using Icinga since its very first days and now we got listed on the Icinga website in the list of known users. Thanks for that, guys.
Check it out at: http://www.icinga.org/users/.