Net-SNMP - Net-SNMP
SNMPSoft Tools - A set of SNMP tools to get, set, walk SNMP tree.
SnarlSNMP - Download snarl-snmp for free.
BlackOwl MIB Browser - Download BlackOwl MIB Browser for free.
qtmib - SNMP MIB Browser
OpenSNMP - Download openSNMP for free. openSNMP is a multi-threaded SNMPv3 engine. This project supports the Simple Network Management Protocol version 3.