Eltima Software: http://www.eltima.com/products/
Virtual Serial Port Driver
Virtual Serial Port Driver creates virtual serial ports and connects them in pairs via virtual null-modem cable. Applications on both ends of the pair will be able to exchange data in such a way, that everything written to the first port will appear in the second one and backwards.
Serial Port Monitor
Serial Port Monitor is a professional and powerful system utility for RS232/422/485 COM ports monitoring. The program monitors, displays, logs and analyzes all serial port activity in a system. This is an ideal way to track down problems that may occur during application or driver development, testing and optimization of serial devices, etc.
Serial to Ethernet Connector
Serial to Ethernet Connector is a solution that will easily let you share up to 255 serial port devices over network (Internet or LAN). It doesn't matter how many serial ports you have: with Serial to Ethernet Connector your computer can have dozens of serial ports with serial devices connected to it. Even if the shared COM port device is physically in the other part of the world you will be able to access it as if it was connected to your computer.