PRTG - Paessler Router Traffic Grapher reached version 188.8.131.520/451.
PRTG is a simple monitoring utility that can be used to monitor almost any item that provides SNMP data plus it has a built in traffic sniffer. PRTG is quite similar to MRTG however PRTG is very simple to install and use. PRTG has a GUI and a built in web server which can be used to view reports. Here is a sample report:
You can read about all features on the homepage of the product.
PRTG is a commercial application, however there is a free version which supports up to three sensors, meaning that you can monitor 3 items. In my opinion PRTG is a very decent tool that can simplify monitoring of various items and events.
You can download various versions of PRTG from this page: