Net Activity is a sidebar gadget, display network activity in real time. It displays two bars (TX/RX) that show your current thoughput. These bars have a text overlay showing you the exact speed that is being acheived. This is a very light weight gadget and has a settings menu that allows you to assign the network card and sampling interval that you are comfortable with.

The license of this software is Freeware, you can free download and free use this network monitoring software.