MRTG is a kick-ass Unix utility which makes cool graphs of traffic loads on routers and other SNMP applications.

MRTG stands for Multi-Router Traffic Grapher. The program queries a network device such as a router for traffic usage statistics, and then it generates an HTML file and a GIF file to present a chronological representation of traffic on a network device.

This program is based on Perl and C and primarily is intended for Unix, but somehow you can make it work on NT. The program exists under the GNU General Public License (GPL). The program is free to use but the author would appreciate it if you bought him a CD from Amazon off his wish-list if you want to show your appreciation for MRTG.