PFConfig - PortForward's PFConfig Software lets you forward ports on any router for any program.
Simple Port Forwarding - Simple Port Forwarding works with WebPages and not directly with your router.
AUTAPF - Reliable TCP and UDP port forwarding for Windows.
PortMapper - Do you need to map a specific TCP or UDP port on your machine to another port on another machine?
socat - socat is a relay for bidirectional data transfer between two independent data channels.
Komodia Relay - Free open source tool to perform TCP based session relay