NetSpot - NetSpot is a free app for wireless site surveys, Wi-Fi analysis, and troubleshooting

netcat - Netcat is a featured networking utility which reads and writes data across network connections...

Vistumbler - Vistumbler is a wireless network scanner for Windows Vista and Windows 7. Features:

Wireshark - Wireshark is a network protocol analyzer for Unix and Windows. It lets you capture and interactively browse the traffic running on a computer network.

Wifi Analyzer - Wifi Analyzer is a handy tool which helps you to select a better channel for your wireless router.

SmartSniff - SmartSniff is a packet sniffer that capture TCP/IP packets and display them as sequence of conversations between clients and servers.