inSSIDer - inSSIDer Essential makes it easy to maintain small business WiFi.
NetSpot - NetSpot is a free app for wireless site surveys, Wi-Fi analysis, and troubleshooting
Kismet - Kismet is an 802.11 layer2 wireless network detector, sniffer, and intrusion detection system.
TamoGraph Site Survey - Wi-Fi site coverage survey and modelling application
Waircut - Free network audit app
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.