coconutWiFi
Coconut Flavour(Free)coconutWiFi: Instantly Check WiFi Network Range
WirelessDriver
Wirelessdriver(Free)How to Uninstall Wireless Baggage Drivers Easily
WiFi2Me
Skyweb Productions(Free)A free app for Mac, by Skyweb Productions.
NetSpot Wi-Fi Reporter
Etwok, LLC(Paid)NetSpot Wi-Fi Reporter - Manage your Wi-Fi networks better
iStumbler
Istumbler(Free)Find wireless connections near your Airport base