NetStumbler is a tool for Windows that allows you to detect Wireless Local Area Networks (WLANs) using 802. It is a freeware WLAN detection application that's reliable and portable.
Here is a screenshot to illustrate the features and user interface of this application:
TekWiFi
Intel PROSet/Wireless WiFi Software
WifiInfoView
Wireless Network Watcher
SoftPerfect WiFi Guard