I have a need to receive SNMP traps from random devices, some of which are not amenable to being added as a network platform because they can't be queried via SNMP. Or if they can, they simply don't have the OIDs HQ wants to check for when adding the new platform.
One example of such a device is the Sun iLOM on their x86 machines. IPMI isn't a suitable tool as they aren't all running Solaris and the contrib. IPMI plugin appears to be meant for use with the local host -- we use some as VMware ESXi hosts, for example, where we can't really run a HQ agent. We need to receive traps from these as there doesn't appear to be any other way of being alerted to hardware failure.
(There are other devices with similar issues on our network, receiving traps is a one-size-fits-all fix that works for us.)
At the moment we're using What's Up Gold, and that seems happy receiving traps from devices without needing to be able to do more than ping them.
Other than this we're pretty impressed with HQ, but if I can't solve this with HQ then my bosses aren't going to be willing to go with it.
I eventually figured this out for myself: the newer Sun gear is using a completely different set of MIBs. Once I found the necessary OIDs I was able to make a new plugin to grab that data, and added the log_tracker plugin type to it so I can receive traps and alert on them.
Of course it looks like every model -- and possibly every iLOM version or host! -- will have these at different points in the MIB. Is there perhaps any way to do lookups within SNMP tables so I can just specify a key to find the right index -- for example, "188.8.131.52.184.108.40.206.220.127.116.11.8.1.4.x" will have the text value "/SYS/MB/T_AMB0", knowing "x" points to the correct OID for the ambient temperature sensor, so if I could somehow tell HQ to do that lookup on each host rather than having to do it by hand and create a unique plugin each variant then that would be fantastic.