I have no idea what the status is of this snmptrapd plugin:
but perhaps it does what you need?
Maybe give it a little TLC and let us know what you did and we can incorporate any enhancements you make to it :}
The snmptrapd plugin can be used for incoming traps (which get internally translated into events).
Monitoring set of values via snmp get/getNext/table walk is currently not
This is to a good deal because discovering those resources at runtime would mean that we need dynamic metadata.
What I can imagine (and this should be pretty easy to accomplish) is to have a base snmpget plugin, that defines the infarstructure and then individual child plugins that use this functionality and define the concrete metadata for one concrete device.
Contatct me if you want to help here.
A base SNMP plugin like Heiko described could potentially leverage the opensource snmp4j library, which is what the RHQ apache plugin uses.