1)   PRTG - Paessler Router Traffic Grapher 5.2.0.581
An easy to use Windows solution that monitors and classifies bandwidth and network usage. The software supports SNMP, packet sniffing and netflow to generate live readings and trend data to optimize the efficiency of your network components.

 2)   Paessler Netflow Tester 1.0
Paessler Netflow Tester is a free program that simply dumps the data of all Netflow packets that a computer receives from a Cisco router. This can be useful when debugging bandwidth monitoring configurations based on Cisco's Netflow protocol.

 3)   Paessler SNMP Tester 1.0
Test and debug SNMP requests with Paessler SNMP Tester for free. Run simple SNMP requests against a device in your network, testing each single step of the SNMP request as it is logged into a logfile for analysis.