Homedale - With Homedale you can search for Wi-Fi / WLAN Access Points and monitor their signal strength.
Surge for Mac - Advanced Web Debugging Proxy for Mac & iOS
Vistumbler - Vistumbler is a wireless network scanner for Windows Vista and Windows 7. Features:
Charles Proxy - HTTP proxy / HTTP monitor / Reverse Proxy
Waircut - Free network audit app
HTTP Headers - HTTP Headers allows you to quickly see the HTTP header information for the current URL.