Alternative apps to Xirrus Wi-Fi Inspector:
The most powerful WiFi Scanner for residential WiFi.
inSSIDer for Home gives you visibility into your Wi-Fi environment.
A simple, yet powerful utility for measuring your bandwidth usage and the speed of all kinds of wired and wireless network connections (Dial-up, Ethernet, ISDN, DSL, 802.11b etc.).
WifiInfoView scans the wireless networks in your area and displays extensive information about them.