I support my parents, wife and daughters computers, and they are rather computer illiterate.   On all of their computers I have the monitoring graphs of gnome 2 in the corner somewhere.

It's very helpful as at a glance, without disrupting the user, I can see what's going on in the system.   ie: if my wife's youtube is sluggish I can see that here purple bar (swap) is half way up.   So I know to tell her to close some of the 200 odd google tabs she has open.   If it's the red (CPU io wait) it's the hard drive doing something, so I can tell her to stop that 200G transfer of files.... etc

With the new gnome 3 I have no idea what the system's doing and have to walk the person through opening a terminal window and running vmstat or top.