inSSIDer - inSSIDer Essential makes it easy to maintain small business WiFi.
Aircrack-ng - Aircrack-ng is an 802.
NetSpot - NetSpot is a free app for wireless site surveys, Wi-Fi analysis, and troubleshooting
netsniff-ng - netsniff-ng is a free, performant Linux networking toolkit.
Vistumbler - Vistumbler is a wireless network scanner for Windows Vista and Windows 7. Features:
WirelessKeyView - Recover lost WEP/WPA keys stored by Wireless service of Windows