inSSIDer by MetaGeek wifi analyzer.

Advanced IP Scanner shows all network devices, gives you access to shared folders, and can even remotely switch computers off.

Acrylic WiFi is a free WiFi scanner designed to scan wireless networks and view WLAN channels, signal, traffic and security.

WeFi is an app which connected to free wifi and cellular networks and provided analytic services.

NetSpot is a software tool for wireless network assessment, scanning, and surveys, analyzing Wi-Fi coverage and performance.

NetStumbler (Network Stumbler) is a tool for Windows that facilitates detection of Wireless LANs using the 802.11b, 802.11a and 802.11g WLAN standards.

Vistumbler is open source WiFi scanner for windows.