Windows only: Bandwidth monitor NetWorx is packed with tools to help you keep on top of what's happening on your network. As shown above, Networx offers network Statistics, Incoming Traffic, and Speed Meter readouts; it also includes traceroute, netstat, and a ping module to help you keep an eye on your network. If you'd like to monitor your bandwidth at the router level to see how much bandwidth everything on your network consumes instead of just one terminal. Networx is a free download for Windows only.

http://www.softperfect.com/products/networx/