HoustonPort.com

Virtual Serial Port ActiveX Control
Allows application to create custom additional virtual serial port in system and fully control it. Created virtual serial ports looks like real serial ports for other Windows applications. [Commercial]
www.mks.zp.ua/

Serial Port Mapper : Program allows you to map any serial ports
Program allows you to map any serial ports to any other serial ports.
www.serial-port-mapper.com/

Virtual Serial Port SDK
Create and manage virtual serial ports from .NET and ActiveX.
franson.com/

Universal Serial Port Python Library
A multi-platform pure-Python module to access serial ports, which currently works on Linux and Windows. [Open Source, GPL]
balder.prohosting.com/

Stokely Consulting - Unix Serial Port Resources
Technical information with pinout data of various serial ports and splitter cables used in Sun's designs.
www.stokely.com/

Virtual Serial Port Kit
Program creates pairs of virtual serial ports connected virtually to each other.
www.virtual-serial-port.com/

Unix Serial Port Resources
Mostly Sun related articles on serial port and console related issues.
www.stokely.com/

Mac Serial Port Interfacing
Tips for interfacing a Mac serial port to RS-232 lab equipment.
francis.courtois.free.fr/

Serial Port Monitor
Professional application for RS232/422/485 COM ports monitoring. It monitors, displays, logs and analyzes all serial port activity in a system, tracks down problems in system or application configurations and processes.
www.eltima.com/

DCC Serial Port Programmer
Serial port DCC decoder programmer that works without special software on any computer running any OS that supports an RS-232 port.
www.sheerstock.fsnet.co.uk/