Scapy - Scapy is a powerful interactive packet manipulation program.
Nipper - Nipper - Neat Internet Protocol Packet EditoR - is a graphical packet generation tool.
Packet Editor - Packet Editor a free packet editing tool to debug winsock based network solutions.
packeth - packeth is GUI and CLI packet generator tool for ethernet.
Advanced IP Scanner - Advanced IP Scanner shows all network devices, gives you access to shared folders, and can even remotely switch computers off. Download it Free.
Pypacker - Pypacker is a fast and simple packet creation and parsing library for Python.