PortMapper - Do you need to map a specific TCP or UDP port on your machine to another port on another machine?
Simple Port Forwarding - Simple Port Forwarding works with WebPages and not directly with your router.
netcat - Netcat is a featured networking utility which reads and writes data across network connections...
Komodia Relay - Free open source tool to perform TCP based session relay
Packet Sender - Packet Sender can send and receive UDP, TCP, and SSL on the ports of your choosing.
Port Map - TheCodingMonkeys, authors of software like SubEthaEdit.