Here are some tips on the known and unknown aspects of your WiFi network. These tools will provide you the basic wireless details such as SSIDs, channels, signal strength, and security status.
Acrylic WiFi for Windows offers non-commercial use. There is no saving or moving functionally except for a feature that will allow you to post a screenshot of Twitter. Both non-commercial use and paid/commercial version support a monitor or promiscuous mode to capture more traffic and also has a built in simple brute-force password cracking utility to test the security password. Although the free edition has a simple but yet attractive and user friendly GUI.
AirGrab WiFi Radar for Mac OS X is one that is a free based WiFi stumbler although there is an optional free registration is required to get rid of their snag screen. The GUI displays the networks and the graphs in a more complex and different way rather than the usual stumblers. During the trouble shooting there the WiFi router shows the noise level which is very helpful.
Cain and Abel for Windows is a multi-purpose password recovery and cracking applications that also features WiFi stumbling, sniffing, and cracking tools. It does have an older look and touch to it. In addition to the typical SSID and signal info, you can also see a list and details of connected clients.