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....
Komodia Relay - Free open source tool to perform TCP based session relay
PFConfig - PortForward's PFConfig Software lets you forward ports on any router for any program.
socat - socat is a relay for bidirectional data transfer between two independent data channels.
PortMapper - Do you need to map a specific TCP or UDP port on your machine to another port on another machine?
Portfwd - Portfwd, Port Forwarding Daemon, stands for port forwarding daemon.