wmsystray provides a system tray compatible with freedesktop.org's System Tray Protocol specification. Basically, it serves as a system tray that allows other programs to show icons in it. For example, if you enable GAIM's System Tray Icon plugin, wmsystray will display GAIM's systray icon. Its intended use is as a Window Maker dock app, though it will run in other window managers as well.
wmmenu is a "dock application" for Windowmaker that provides a button bar to launch applications from. The bar opens automatically when the mouse enters the button. Multiple instances of the program can run at the same time; each one provides a menu that it reads from a separate file, so you can have as many different menus as you want.