Eltima Serial Port Monitor
Serial Port Monitor is a professional application for RS232/422/485 COM ports monitoring. It monitors, displays, logs and analyzes all serial port activity in a system. It can effectively be used for monitoring serial data exchange between serial devices and any Windows application, debugging... Serial Port Monitor supports all COM-port types: standard on-board ports, extension board ports, SERIAL-via-USB adapters. ... Serial Port Monitor is a powerful system utility for exploring the way OS works, monitoring how applications use ports, for tracking down problems in system or application...
http://www.mks.zp.ua/serial_port_monitor.exe - 3Mb - Download - Screenshot

Advanced Virtual COM Port
Advanced Virtual COM Port is the first software of its kind which includes both local and network virtual COM port functions. It can share your real COM ports or it can create virtual COM ports and connect them with a virtual null-modem cable locally or through a TCP/IP network or the Internet. ... You can connect to a shared port and use it just like it is on your machine. ... Virtual serial ports created by the program look and work the same way as real ones look and work.
http://www.advancedvirtualcomport.com/files/AdvancedVirtualComPort.zip - 1Mb - Download - Screenshot

IPAppmon
Are you an over-worked network administrator? Get calls complaining about system outages you have no way of monitoring? Don't know if your payroll server is up or down? Rest easy. AppMon makes it easy to run applications and monitor them from your current network monitoring package.... ... STEP 3: Configure your network monitoring tool* to monitor the appropriate TCP/IP port where AppMon resides. ... If any one of the Applications started by AppMon fails (or is accidentally closed), you will be notified visualy, audibly, by email and through your network monitoring tool.
http://www.ipworx.com/product/appmon/appmon4.zip - 4Mb - Download - Screenshot

IPCheck Server Monitor
IPCheck Server Monitor 5 helps organizations monitor critical network resources and immediately detect system failures or performance problems. It offers reliable network and website monitoring using Paessler's IPCheck? Technology, fast and easy installation, support for Windows NT/2000/XP/2003... Various sensor types including PING, PORT, HTTP, HTTPS, Advanced HTTP, HTTP Transaction, DNS, SMTP, POP3, SNMP and custom sensors are supported for in depth monitoring of almost any network device. ... The Freeware Edition monitors up to three sensors and is limited to PING, PORT and HTTP sensors...
http://download2.paessler.com/download/ipcheck.zip - 16Mb - Download - Screenshot

Easy Network Service Monitor
Easy Service Monitor is a network fault management tool that continuously monitors network devices and services. If something went wrong, it will alert you by email/phone/pager BEFORE problems get seriously out of hand. A detailed log file will record every event of the monitored targets and can... You can configure the system so that when something goes wrong, a set of actions, such as execute a program, reboot server or update web page, will be triggered.
http://www.javvin.com/emonitor.exe - 2Mb - Download - Screenshot

Network Configuration Management
Network Configuration Management is a set of utilities that manage network config, diagnose and monitor network, it includes: IP Manager: create different TCP/IP settings profiles, and switch between them instantly without reboot. All you need is just to configure ONCE any of your possible... Socket to Process Mapper: monitors all open TCP and UDP ports in your local computer, and maps ports to owning application so you can find out which program has opened which port. ... Bandwidth Monitor: shows your connection speed in real time.
http://www.missilesoft.net/downloads/ncm.exe - 4Mb - Download - Screenshot

MSN Track Monitor
MSN Track Monitor is a msn spy and MSN sniffer to spy MSN chat on network. It is able to hack and monitor MSN conversations automatically. All intercepted messages can be saved as HTML files for later analysis. You can choose whether open the HTML files automatically after you save it manually. ... if the 2-layed devices is switch, you should do span or port monitor, and MSN Track Monitor will spy MSN messages too. ... In your network, if the 2-layed devices is HUB, MSN Track Monitor will spy MSN messages.
http://www.tallsoft.com/MSNTrack_setup.exe - 918Kb - Download - Screenshot

Advanced Administrative Tools
Have you been port scanned lately? Completely ignoring network security is not smart and ignorance isn't exactly bliss. If you access the Internet via a cable modem, DSL, or even a dial-up connection, someone is always knocking on your virtual front door, giving your system the once-over. ... Further, AATools Network Monitor maps the ports in use to their respective applications (this feature is available under Windows NT/2000/XP) providing a simple and easy solution to tracking application to port maps.
http://mirror1.glocksoft.com/aatools.zip - 3Mb - Download - Screenshot

MegaPing
MegaPing is the ultimate must-have toolkit that provides all essential utilities for Information System specialists, system administrators, IT solution providers or individuals. It includes: Scanners: Comprehensive Security Scanner, Port scanner (TCP and UDP ports), IP scanner, NetBIOS scanner,... Other features include multithreaded design that allows to process any number of requests in any tool at the same time, real-time network connections status and protocols statistics, real-time process information and usage, real-time network information, including network connections, and open...
http://www.magnetosoft.com/downloads/megaping_setup.exe - 4Mb - Download - Screenshot

PortMarshaller
PortMarshaller is a software-based TCP/IP port forwarder and network monitoring service. The software accepts connections on a particular TCP port, and establishes connections to a different TCP port to fulfill requests. This capability offers a solution to various network topology problems. ... Optionally integrates with Internet Information Services (IIS) for its advanced abilities. ... Administrative web interface allows the monitoring of connection and data transfer statistics.
http://www.portmarshaller.com/portmarshaller.zip - 303Kb - Download - Screenshot