TCPWatch 1.3 (by Shane Hathaway)
TCPWatch is a utility written in Python that lets you monitor forwarded TCP connections or HTTP proxy connections.

It displays the

netstat-nat 1.4.7 (by D.Wijsman)
Netstat-nat is a small program written in C

TCP Track 1.1.5 (by Steve Benson)
tcptrack is a sniffer which displays information about TCP connections it sees on a network interface

VNC Reflector 1.2.4 (by Constantin Kaplinsky)
VNC Reflector project is a specialized VNC proxy server.

VNC Reflector is a specialized VNC server which acts as a proxy between a

prtunnel 0.2.7 (by Josh Beam)
prtunnel is a program that can tunnel TCP/IP connections in a variety of ways, including through HTTP and SOCKS5 proxy servers

Symbion SSL Proxy 1.0.5 (by Szilard Hajba)
SSL Proxy server listens on a TCP port, accepts SSL connections, and forwards them to another local or remote TCP port.

For example,

sslredir 0.9.1 (by Jason Tackaberry)
sslredir is a simple utility used for redirecting incoming non-SSL connections to outgoing SSL connections.

sslredir project is usef

wminet 3.0.0 (by Alan Swanson)
wminet is a very useful dock app for monitoring internet connections to and from your computer.

The number of connections can be f

tcptunnel 1.0 (by Dan Goldwater)
tcptunnel is a simple TCP tunnel written in Perl.

Also is a versatile tcp tunnel

HAproxy 1.3.3 (by Willy Tarreau)
HA-Proxy is a TCP/HTTP reverse proxy which is particularly suited for high
availability environments

GKrellM 2.2.10 (by Bill Wilson)
GKrellM application is a GTK-based stacked monitor program that charts SMP CPUs, disks,

lm_sensors 2.10.1 (by Mark S.)

Loggerithim 7.0.1 (by gphat)
Loggerithim is an extensible monitoring and remote management package

SmokePing 2.0.9 (by Tobias Oetiker)
SmokePing is a delux latency measurement tool

Pipe Viewer 0.9.6 (by Andrew Wood)