DU Meter

DU Meter is a nice little system tray application which shows you how much bandwidth is currently being used. The application is simple and straightforward. Simply install the program and it will be up and running, and it will restart each time you log in or start up your computer.

I like this product (which is very cheap) because it gives me an idea of how my bandwidth utilization is doing. If my computer seems sluggish or the internet is "slow" I can glance at the graph and see what's happening.