For a change, would you like to have an applet (a small application/plugin which uses the already existing desktop environment such as Gnome or Qt-KDE, etc) that displays "fires" as a way of resembling the CPU usage!. Yep, it's pretty cool :). It's called CPU-Fire Applet.
The more flames there are the more your CPU is being used. It's pretty simple. Although onlike with others such as the Syspeek where you can guess the amount/percentage of the CPU is being used (rough values) without having to completely open the application with CPU-Fire, it may not be that easy to "read" the rough values, but I like it :D.
|"My CPU's on fire with passionate lo..." what! :P|
*. Change the size.
*. Change update interval and the sensitivity (will add more flames even for a small CPU usage change).
*. Bring your mouse hover over the icon and it'll display a live updating CPU-usage (continuously - as long as the hover is there).
You can install CPU-Fire applet in Ubuntu 11.04 (should work in 10.10 and 10.04) by entering the below command in your Terminal.
sudo apt-get install cpufire-applet
Once installed (only for Gnome classic desktop), right click on your panel and choose "Add to Panel". In the applets list you should see the CPU-Fire (around the top ones). Just click on it and it'll be added to the panel. You might need to log-out or restart the Laptop/PC if the applet is not in the "list". Enjoy it.