This is a great little free application, I have used it for years, I am lost without it.
It allows you to monitor various system processes at the top of the screen as part of OSX Finder.
I set it up to show:
- Network Transmit and Receive activity
- Ram Usage
- CPU Loading
This is how mine looks:
This is fantastic if you are unsure if something is encoding, downloading, uploading or generally hogging all the RAM.
http://www.ragingmenace.com/software/menumeters/
It is a preference panel for the system preferences.