NetStumbler - Official source of information about Netstumbler.
NetSpot - NetSpot is a free app for wireless site surveys, Wi-Fi analysis, and troubleshooting
Vistumbler - Vistumbler is a wireless network scanner for Windows Vista and Windows 7. Features:
Kismet - Kismet is an 802.11 layer2 wireless network detector, sniffer, and intrusion detection system.
NetSurveyor - NetSurveyor is an all one network diagnosing and troubleshooting tool for the Windows operating systems.
Wifi Analyzer - Wifi Analyzer is a handy tool which helps you to select a better channel for your wireless router.