AdventNet ManageEngine OpUtils 

The AdventNet ManageEngine OpUtils is a comprehensive set of 40+ unique system and network monitoring tools. This web-based software helps IT administrators monitor, diagnose and troubleshoot their IT resources. OpUtils is web-based and very quick.
network utilities system utilities network tools switch port mapping network troubleshooting network monitoring cpu monitor memory utilization diagnostic tools bandwidth monitoring cisco router monitoring address monitoring cpu desktop monitoring snmp monitoring

FreeSnmp 

Free SNMP provides basic support for SNMP protocol, allowing users to perform such tasks as viewing MIBs, performing Walk operation.The tool is designed with a user-friendly interface and is easy to use.
network management discovery mac addresses snmp monitor browser network tool network software net tools network monitoring network utils

NetworkView 

NetworkView is a compact network discovery and management tool for the Win32 platform : in a few minutes, it will discover all TCP/IP nodes and draw a full graphical map using DNS, MAC addresses, SNMP, WMI, NetBIOS and TCP Ports information.
network discovery network management network management discovery snmp netbios wmi mac addresses monitor mib browser port scanner

SNMPGetSet 

A little tool to get and set SNMP standard data and individual data. Works on predefined MIB2 OIDs and self-defined OIDs. A little buggy but I just threw the code down and compiled it for use on one project.
snmp oid get set

Analyse It 

Analyse It is a SNMP network interface utilization and error, graphical reporting tool. Enables network availability, performance, reliability and utilization reporting.
snmp tool monitor report network graph analysis free response time graphical ip accounting cisco nortel

AdventNet Simulation Toolkit 

Creates a virtual lab with 50,000+ devices for testing, training and demos. Support for SNMP, TL1, TFTP, FTP, Telnet and IOS devices with Traps & Informs, Autonomous Msg, Jython script, agent management via RMI , PDU Scrambler and Customization.
network simulator network simulation snmp agent simulator agent simulator snmp simulator