inSSIDer - inSSIDer Essential makes it easy to maintain small business WiFi.
Homedale - With Homedale you can search for Wi-Fi / WLAN Access Points and monitor their signal strength.
NetSpot - NetSpot is a free app for wireless site surveys, Wi-Fi analysis, and troubleshooting
iBwave Wi-Fi - iBwave Wi-Fi software suite brings smart networking solutions to enterprise, education, hospitality, transportation, retail, office, healthcare, public venues, and residential wireless networks.
Waircut - Free network audit app
Kismet - Kismet is an 802.11 layer2 wireless network detector, sniffer, and intrusion detection system.