After fighting with the Nagios event broker ndomod for a few weeks, I finally found the answer to why it wasn’t working. (ndomod Could not open data sink!)
Apparently, there is a bug in the Ubuntu x64 version that keeps it from correctly reading the location of the socket file. So, you need to specify the default locations for two (2) files, ndomod.conf & ndo.sock.
Once I specified them, I just restarted nagios3 & ndoutils and everything worked fine. The locations are /usr/local/nagios/etc/ndomod.conf & /usr/local/nagios/var/ndo.sock.
The symptoms can be found in /var/log/nagios3/nagios.log:
 Nagios 3.2.1 starting… (PID=1954)  Local time is Sat Mar 05 22:07:41 EST 2011  LOG VERSION: 2.0  ndomod: NDOMOD 1.4b9 (10-27-2009) Copyright (c) 2009 Nagios Core Development Team and Community Contributors  ndomod: Could not open data sink! I’ll keep trying, but some output may get lost…  Event broker module ‘/usr/lib/ndoutils/ndomod-mysql-3x.o’ initialized successfully.  Finished daemonizing… (New PID=1985)
The key line is “Could not open data sink!”