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.
NetSetMan - Are you tired of changing your network configuration on your laptop every day?
netcat - Netcat is a featured networking utility which reads and writes data across network connections...
TCP/IP Manager - Designed to help computer users keep track of their network configuration in different locations.
Ettercap - Ettercap is a suite for man in the middle attacks on LAN.
Net Profiles - With Net Profiles, mobile computing becomes a whole lot easier.