You never know when you might have to monitor a router or switch (or even your home network, right?). MRTG has been around for quite some time, and has matured into a VERY good traffic monitoring and graphics package. I've used it as a long-term (daily/weekly/monthly/yearly) tool for a NOC full of Cisco routers, and a dextrous hand with configuration can produce quality tracking for just about any SNMP-enabled network device. In fact, my test for the Gurubox build is my home DSL connection, which is controlled by a SpeedStream 4200 DSL modem. The build from source was absolutely painless. If you're looking for a quick-and-easy "network status" webpage, MRTG is the perfect tool with which to build it.
MRTG - Tobi Oetiker's MRTG - The Multi Router Traffic Grapher