Kismet - Kismet is an 802.11 layer2 wireless network detector, sniffer, and intrusion detection system.
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:
Aircrack-ng - Aircrack-ng is an 802.
Wifiner - WiFi Analyzer - WiFi Analyzer. See your WiFi signal on a visually comprehensive map and make sure you are getting the best of your network
Wifi Analyzer - Wifi Analyzer is a handy tool which helps you to select a better channel for your wireless router.