Any ITPro that had to guide a user on how to setup or troubleshoot a PC problem on the phone, knows the frustration of trying to explain the user where to click or understand from his description what he see on the screen.
In such cases I recommend on using the original manufacturer's user guide that is usually downloadable from the web. the user-guide usually contains screenshots of the menus and settings.
Check out: Edimax, Linksys, Belkin, LevelOne
TP-Link even created an online simulator for popular models: TL-WR541G , TL-WR542G
Another helpful site is PortForwarding.com which gives instructions and screenshots of various routers on how to open specific ports for an application/service.