WMab is a Window Maker dockable application that allows ACPI laptop users to graphically monitor the status of their power sources (i.e., whether or not AC or batteries are in use, and how long it will take to drain or charge the batteries). It also works with official kernels and with all Intel ACPI patches.
Sherman's aquarium is a screen saver, a GNOME panel applet, and a dock applet that provides an aquarium with fish and/or turtles. In applet mode, it can display lots of information, such as CPU load, temperatures, memory usage, and many other things. Both the applet and the screensaver are very configurable.