FAM allows gnome to do such useful things as automatically update the menu when new applications are installed, and refresh nautilus when a directory it is viewing is changed.
See Configuring FAM for instructions on how to install it.
Gnome System Monitor
This application appears when the "System Monitor" applet is clicked. It is not installed be default in the gnome group, so you need to install it separately using:
pacman -Sy gnome-system-monitor