socat - socat is a relay for bidirectional data transfer between two independent data channels.
PFConfig - PortForward's PFConfig Software lets you forward ports on any router for any program.
Komodia Relay - Free open source tool to perform TCP based session relay
Robusta Port Forwarder - This tool is created with the primary intention of making it easy to the end user to set forwarding rules in his router....
Simple Port Forwarding - Simple Port Forwarding works with WebPages and not directly with your router.
Port Map - TheCodingMonkeys, authors of software like SubEthaEdit.