Measure your system load in Ubuntu 12.04 via the handy appindicator System Load Indicator

System Load Indicator is a handy tool that displays various system informations on the Unity panel, making them easily perceivable via vividly colored filled squares.

By default, System Load Indicator exposes the processor and the memory usages, "mode" that can be enriched by selecting Network, Swap Space, Load and Harddisk under System Load Indicator/Indicator Multiload appindicator-->Preferences-->Monitored Resources-->check the desired items

The indicator comes with a decent tweaking availability, consequently, users can adjust the colors used to represent the amount of usage per "tracked" item (like for instance, changing the cached memory's color to red as opposed to the used memory's to green, in order to trigger an "abrupt" contrast) as well as the width of the "boxes" in which the indicators run.

How do we install System Load Indicator 0.3?
Add the following PPA (Natty, Oneiric, Precise, Quantal)

sudo add-apt-repository ppa:indicator-multiload/stable-daily

sudo apt-get update
sudo apt-get install indicator-multiload

Launch System Load Indicator via the Dash by typing system load indicator in the search area.