PortMapper - Do you need to map a specific TCP or UDP port on your machine to another port on another machine?
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:
Komodia Relay - Free open source tool to perform TCP based session relay
Kismet - Kismet is an 802.11 layer2 wireless network detector, sniffer, and intrusion detection system.