I will use this page to collect ip port information, tips and resources. If there is a good resource on the net which is not here, :

• Active Ports for NT/2000/XP
  
• FreeBSD Ports
  
• Port Lookup : Port Knowledgebase
  
• Port Lookup : Treachery Unlimited
  
• Port Lookup : seifried's list
  
• Port Lookup : simovits list
  
• Port Lookup : TCP/UDP Port and Service Search
  
• Port Lookup : wittys list
  
• FAQ on Port Probes
  
• SANs : What port numbers do well-known trojan horses use?
  
• TCPView lists TCP and UDP endpoints in Windows
  TCPView is a Windows program that will show you detailed listings of all TCP and UDP endpoints on your system, including the local and remote addresses and state of TCP connections. On Windows NT, 2000 and XP TCPView also reports the name of the process that owns the endpoint. TCPView provides a more informative and conveniently presented subset of the Netstat program that ships with Windows.
• Windows NT, Terminal Server, and Microsoft Exchange Services TCP/IP Ports
  
• Windows 2000 Port Assignments for Commonly-Used Services