WMBlueObject displays a spinning 3D object using OpenGL rendering. It runs as a dockapp. You can choose the object by clicking on the window, or with the command line option '-o'. If you have a scroll wheel on your mouse, you can zoom in and out using it.
Pywmsysmon is a dockapp that displays your current CPU and memory usage. It has a graph displaying the history of the CPU usage and a bar to display the current amount of memory in use.
Temperature.app is a Window Maker applet which fetches local temperature information every 15 minutes from http://weather.noaa.gov and displays it (in Celsius or Fahrenheit).
WMZCalock is a dockapp calendar clock for use with Window Maker and other X window managers. It features a number of different time modes and the ability to change its colors and fonts.