Almost two years ago I uploaded some nagios plugins to nagiosexchange.com, nowadays monitoringexchange.com. I make the downloads available via my own website too so if you are looking for some plugins these might be handy:

• APC check_apc_ups
  Plugin to check the status of different APS UPS systems.
• APC check_apc_env
  Plugin to check the temperature and humidity status via snmp of a APC Environmental module.
• MGE check_mge_ups
  Plugin to check the status of an MGE UPS system.
• check_snmp_barracuda
  Plugin to check the status of the three mail queues of the barracude mail and spam filter system.
• check_snmp_brocade
  Plugin to check the status of Brocade SAN switches Brocade 4900  and Brocade 5000
• check_snmp_nortel_core
  Plugin to check the status of Nortel core routers (Passport systems or currently named Ethernet Routing Switch).

They are available for download here. Enjoy! And leave a reply if you use them, I'd much appreciate that :)