MenuMeters

Now, thanks to MenuMeters, you can monitor various parameters of your computer's activity without opening an application or leaving your current window.

MenuMeters is installed as an option on the System Preferences panel, from which you can decide what aspects of your system performance you want visible from your task bar.

MenuMeters can report on CPU usage, disk activity, memory status, and network traffic. The data can be displayed numerically, in graphs, or by combining both forms. The colors can also be customized.

Information on memory usage, processor usage, and Internet connection performance are also available from MenuMeters.